﻿ANCYLUS. 



Genus ANCYLUS. Geoffroij. 



Mol.r.cscUM AQUATICU3I. Tesiii patolll/onui.<, pl'rnmque 



siii'isirulis, nonsijmmeirica, ejyiilfiiniih; iiidnta, 



(ijiice suhlaterali, siihs^pi'raU; ojx'n-iiliini iiiillimi. 



MiM.l.USC, KHESHVVATER. Shell patellifonu, geucrally 



sinistral, uon-symmetrical, covered with an 



epidermis, apex sublateral, subspiral ; operculum,' 



none. 



Like the Limnreiidw, the Ancyli are found in ponds 



and rivers of fresh water, and like them are capable 



of lixiny; at times uncovered by water. They are 



found in all climates. We have two well-known 



British species. Others exist eastward in India and 



westward in the United States ; southwards, we have 



Brazilian and Peruvian -pfciis, .and the first and 



finest sjieeies on our list, .1. Ciiiuinijian iit:, dates from 



Van Diemen's Land. 



Species 1. (Fig. a, h, c, Mus. Sowb.) 



AncVMJS ClfmINGIANUS. Anc. testa iim/innlr ,;ili/n'. 

 fiinui, liiihovafa, posiice awjndil, milii-r iniijJi'i, 

 ri,i,lrn„i,l,'„!;va,;:. i,,,],,/,!: 'd„r^n rlmih,, n^hnnh,, 



l„lrrni;irr r„l,lr prnJnrt,:, ,nii.<p!n,li. 



Ci'.MiN'j's A.\OYLUS. Shell deeply cup-shaped, sub- 

 ovate, narrow behind, full in front, covered with 

 an olive epidermis ; back elevated, rounded, 

 radlately ribbed, apex posteriorly submarginal, 

 laterally much produced, uuispiral. 



Bouu.;ni.;nat. Troc. Zool. Soc. ISr,^. PI. XX. f. 



Ilah. Van Diemen's Land. 



Species 2. (Fig. a, h, Mus. Brit.) 



Ancyi.us textilis. Aiic. testa Jcpn'ssd, epidennide 

 stramiiu'd, ad manjiuaii Iriiinii'scciis itidiitd, 

 radlatlm costatd, conceidrtrh trniitsstine striata, 

 iiUns castaiirrl; dorso di'j^resso, apice ohtuso, siih- 

 lairrati. 



The tisXTIle ancvlus. Shell depressed, covered with 

 a straw-colotired epidermis, becoming brown at 

 the margin, radiately ribbed, concentrically very 

 tinely striated ; back depressed, apex obtuse, 

 sublateral. 



Gurrr. Proc. Zool Soc. 1870. PI. XVIL f. D-U. 

 Hah. Trinadad. 



Species 3. (Fig. a, h, r. d, Mus. Brit.) 



AnCYLUS FLUVIATILIS. Ahc. testa nraJn-s,(hi-i 

 tenui, piallklh straviined, vet earidr,:, ^hIi 

 dorso declivi ; apice postice siihniariiiiial, 

 ceiitrali. 



The river Ancylus. Shell ovate, rather round 

 pale straw or blueish, subconical, back si 

 apex posteriorly submarginal, subcentral. 



Gmelin. Linn. Syst. Nat. 



Patella rostrata. D'Argenville. 



Patella cornea. Poiret. 



P.Uella vieridionalis. Beck. 



Anci/Ius simplex. Bourguignat. 



Hah. Great Britain, and Europe generally. 



o])ed ; 



Species 4. (Fig. a, li, Mus. Brit.) 



Angylus LAersTRls. Aiir. te:^td sidiuriild, eloihjal,!, 

 teiuii. I.ilrraliirr sid.ran, j.rrs.d . a.dirr ,],l,at- 

 leiniald, epidermnU- fiism ,„diitd ,• d,<rs„ Iriimsslnie 

 ritdiatiia striata; apice -pustero-lateraH. 



The lake anctlus. Shell subovate, elongated, thin, 

 laterally rather compressed, anteriorly snb- 

 attenuated, covered with a brown epidermis ; 

 back very finely radiately striated ; apex postero- 

 lateral. 



LiNNJius (Patella). Syst. Nat. 



Patella ohluiuja. Ddlwyn. 



Hah. Great Britain, and Europe generally. 



Species 6. (Mus. Brit.) 



Ancylus Caffka. Atic. testa suboUvaceo-cor)ied, reyn- 

 lariter ovatd,profundii cahjciforml, Icerigatd ; dorso 

 elevato, arcuato ; apice postero-siiblaterall, acii- 

 minato. 



The Caffeb Ancylus. Shell subolive-horny, regularly 

 oval, deeply cup-shaped, smooth ; back raised, 

 arched ; apex posteriorly sublateral, acuminated. 



Krauss. Siidafricanischen Mollusken, T. IV. PI. 

 XIII. 



Hah. South Africa. 



This has a much more pointed apex than Ancylus 



Cumingianus, which is the only other species with so 



rounded a back. 



