A P L U S T R U M 



Gemis APLUSTRUM. 

 '/V-s/« ijlohoHO-omla, spird proiluctd, planimculd ; aperiiira 

 ohlnnga, mhcanaliculaia, silbeniargiualn. labiuiii iii- 

 feniuiii HuUitm; columella promineii a, incnlnia. siib- 

 for/iin, oblique trimcaia, marguie hik-rno tmiiasxiuio, 

 siibrcplirato ; nmb'dicus nnlliis. 

 Shell irlobosely ovate, with protluced, rather flattened 

 spire ; aperture oblong, with a slight canal, subemar- 

 ginated, inner lip none ; columella prominent, invo- 

 lute, slightly tortuous, obliquely truncated, internal 

 margin very thin, somewhat reflected ; no umbilicus. 

 The species Bulla apliislre, of antliors, , upon which 

 this geiuis is founded, is from the Mauritius. The other 

 two smaller species, very doubtfully admitted in the 

 nenus, are both from the United States of America. The 

 animal is similar to that of Hyflatbm, from which the 

 shell differs in having a produced spire in wliieli all the 

 whorls arc visible. 



Species 1. (Mu". ? copied.) 



\pi,lsTiiUM GouLDll. Apl. iestd pared, oratd, coiivo- 

 lutd,fragtli, palUdd, nitidd, semipellucidd, transverse 

 k'viter striatd ; spird depressd, discoided, imperforatd, 

 iiiU-rdum prominuld, anfractibus quatuor, superne ro- 

 Itmdatis, sutiiris impressis ; apertnrd supra angustd, 

 cersitu basin dilatatd ; columelld arcaatd, alba, nitidd, 

 li.ipcrforald. 



liiULD's ApLUSTKUM. Shell small, ovate, convolute, 

 fragile, ])ale, smooth, scmipeDucid, transversely 

 slightly striated ; spire depressed, discoidal, imper- 

 forate, sometimes prominent, whorls four, rounded 

 above, with sutures impressed ; apertui-e narrow- 

 above, dilated towards the base ; columella arched, 

 white, smooth, imperforate. 



CoNTHOY, Boston Journal of Natural History, vol. ii. p. 

 1S3. pi. 4. f. 6. 



llab. Massachusetts Bav, United States. 



Species 3. (Fig. a-g, Mus. Cuming in Brit.) 



Aplustrum thalassiakchi. ApL testa ovatd, subfur- 

 binatd, Iceviyatd, tenni, fasciis latis roseis et lineis 

 nigris margiuatis cinctd, spird produetd, subplanatd, 

 anfractibus rotundaiis ; apertnrd antice canaliculatd ; 

 columelld tenni, rt-flexd. 



The admiral's Aplustrum. Shell ovate, subturbinate, 

 smooth, thin, girt with wide rose-colom-ed bands and 

 black lines; spire produced, rather llattened, with 

 ronnd'ed whorls ; aperture with a canal in front ; 

 columella thin, reflected. 



Martini, Chemn., vol. x. t. UO. f. 1.35(1, 1351. 

 Aplustrum fascintuiii, Schum. 

 Bulla aplustre, Linn., Lamk., etc. 

 Jplustra pulchella. Swains. 



IJdb. Mauritius ; in mud at mouths of rivers. 



The number and distance of the black lines which edge 



the broad pink bands are much varied in this species. 



Species 3. (Mus. Cuming in Brit.) 

 APLU.STRUM DEBILE. Apt. testd obliqui ovatd, pared, 

 pellucidd, corned, inflatd, leevi, subimbilicatd ; spird 

 distirtctd, plana, anfractibus quatuor ; columelld sub- 

 recta, antice abrnple truncatd ; aperlurd ampld, an- 

 tice dilatatd. 

 The weak Aplustrum. Shell obliquely ovate, small, 

 pellucid, horny, inflated, smooth, subumbilicated ; 

 spire distinct, flat, with fcuu- whorls; columella ra- 

 ther straight, anteriorly Mbniplly truncated; aper- 

 ture wide, dilated in front. 

 Gould, Silliman's Journal, vol. xxxviii, p. 196. 

 Hab. United States, America. 



This and the first species are small, horny shells, which 

 are not placed in the genus without hesitation ; but as the 

 earliest whorls are rather produced, and not sunk, as in 

 Hydatina, they seem to come with a greater degree of 

 propriety next to the " Admiral's Bulla." 



July, 1868. 



