my snail project , help with id

i have been collecting snail egg masses from a tank that houses mexican turbo , astrea , pacific nassarius , tongan nassarius , tiger nassarius and cerith snails .
i believe the masses are from the cerith snails but i havnt been able to catch them in the act to verify .
every time i find the masses there are mex turbos near them on the glass but i think it may be a coincidence because the masses do not resemble turbo snail eggs that i have seen .
i would like help id'ing the snails i am trying to culture .
 
here is a shot of the egg mass as it was laid on the glass before collkection

 
the egg mass after collection


 
a video of the velligers without magnification after hatch

 
some magnified stills of the velligers 



 
a video to show locomotion. please excuse the quality this was taken thru my camera phone

 
the egg masses hatched in 5 days . the velligers in these shots are about 4 days post hatch. no sign of settlement thus far
i have been feeding small amounts of I.A. and combating NH3 with chloram x.
well this is what i have so far .
if i can get an id i will start a journal .
 
 

i still havnt been able to catch the snails in the act but am still collecting eggs. 
i know i cant really expect an id from the egg mass but does anyone have any guesses ?
the velligers dont look like cerith shells. 

I'm not good with snail IDs so I tossed it up on FB.

http://www.fishtalpropagations.com/#!home/mainPage
"Making captive breeding easier."

whats FB tal ?
thanx though

oh maybe fish base ? 
nothin makes sense before my second pot of coffee 

The egg mass on the glass looks like what I have always known to be Cerith snail eggs, but I have never verified that.  I don't think velligers' shells are any indication of their adult shells, but I haven't verified that either.  Sorry, that's all I got.

Facebook

http://www.fishtalpropagations.com/#!home/mainPage
"Making captive breeding easier."

Looks like you have a wait in store for you. The whorls at the end of the shell are really tight, which suggests a slow developer with a longish pelagic period.
 
Can you tell if they are taking the I.A.? If they are, then just keep them in good water conditions with lots of food and wait it out.
 
Meta might be harder: Some inverts go through metamorphosis just when they are ready. Others need specific environmental cues or they will never go through it. They just stop development until they finally die. If they look ready to go but seem stalled, try adding some small flakes of aged substrate from the parents' tank. Make sure to get some coralline in there as many species seem to really cue on that.
 
Good luck!

--Andy, the bucket man.
"Not to know the mandolin is to argue oneself unknown...." --Clara Lanza, 1886

great info guys thank you !
i do like the idea of breeding snails although cerith probably wouldnt be my first choice . 
i really like tiger nassarius snails (the big ones) i have a couple of them but cant seem to find out what genus and species they are . without that info it makes researching them a little difficult . if anyone has any info on these please do share.
as far as the cerith veligers they do clear the I.A. but it seems they are sensitive to the NH3 it produces and possibly sensitive to chloram-x to counter act it .
i had better results with some small additions of live algae . all i had was an old bottle of DT's . 
being that i ran out of the DT's i think i will need to set up a larger rearing container with a deep sand bed to help with the break down of waste and also maybe help with settlement cues . i hope this will allow me to use I.A. a little more liberally . 
the cool thing about these guys is that they dont seem to be very dirty animals . all the waste generated comes from the break down of and decomp of the algae paste i add . 
ammonia tests come up nil when i use live algae. 
 
 

 
Nassarius distortus

The scientists that rear snails tend to give the larvae a new container every day. Any chance you could get some more DT's? Even if you just used a little every day with the IA, that might help.

--Andy, the bucket man.
"Not to know the mandolin is to argue oneself unknown...." --Clara Lanza, 1886