﻿R I S S A. 



Fig. 1 h, Elssoa dentu-ulata. See Tlate I. 

 Species 48. (Mus. Sowerliy.) 



RiSSOA SOLUTA. Eis. (Setia) te^tit miiumd, ovalu, 

 alba, spiraliter striata; anfractibiis tribus, brevi- 

 bus, rotuiidi's, nltimo ventricoso, siibsolnto, umbili- 

 cato ; apcrturd rotunda, labia extfrno rectiihculo. 



The loose-coii.ed Rissoa. Shell veiy small, oval, 

 white, spirally striated ; whorls three, short, 

 round, last ventricose, a little uncoiled, umbili- 

 cated ; aperture round, outer lip rather straight. 



PniiJiTi. Moll. Sic. Vol. II. p. 130, PI. XXIII. f. 18. 



Hah. Britain. 



Species 4i>. (Mus. Jeflreys.) 



Rissoa Alderi. ii'w. (Setia) testd minutd, pallid!; 

 fiilvd, Imvi, suhovatd; anfractibtis qidnqne, rotimdis, 

 elevalis, ultimo ventricoso, sttbumbilicato ; aper- 

 iurd subocatd, lahio extenio tenni, columella 

 rediihculd. 



Alder's Rissoa. Shell minute, pale, fulvous, smooth, 

 rather oval ; whorls five, rounded, elevated, last 

 ventricose, slightly umbilicated ; aperture rather 

 oval, outer lip thin, columella rather straight. [ 



Jeffreys. Ann. and Mag. of Nat. Hist. August, 1H.'.8. 



Hub. North Britain. I 



Species 51. (Mus. Brit.) 



Rissoa anatina. Eis.(Hydrobia) t.st,! )tiiiiiil,;,sulr;ridi 

 teiiui, ovafo-snbiilobosd, spiri! /»/■/(■/, apiec ariit" 

 aiifractilin.-- ,jiiiii,/ii,; rai^'dr r,;:-.r,iit;hiis', di.-ili,iiily 

 prope siilnn,,,! aiiqulati.^, itUi ,ii„ sidhjlol.,,.-,, 



snlur 



u„/;,;.l:fd: 



^iihnilnndd. 



The nn k"s Rissoa. Shell small, rather green, thin, 

 ovato-subglobose, spire short, apex acute ; whorls 

 five, rapidly increased, distinct, angular near the 

 suture, last subglobosp, suture channelled ; aper- 

 ture rather round, margin thin. 



Draparnaup. Moll. Terr, et Fluv. de France, p. ;C 

 PI. I. f. 24, 25. 



Jlab. France, England. 



Species 50. (Mus. Sowerby.) 



Rissoa fulgiha. Eis. (Setia) irst,! n-imitd, j'uh-d, 

 liTci, nitenti, castaneo spirnlili r hif,ixri,it,'i^ sj:ii;i 

 brevi, obtnsd ; anfradibus trihu.<, rut imdi^ ; apfr- 

 tiird rotunda, margine tenui. 



The URir.HT Rissoa. Shell minute, fulvous, smooth, 

 shining, with two chestnut spiral bands, spire 

 short, obtuse ; whorls three, rounded ; aperture 

 rounded, margin thin. 



Adams. Trans. Linn. Soc. Vol. III. p. 254. 



Eab. Britain and Ireland. 



Species 52. (Mus. JefTreys.) 



Rissoa eximia. Eis. tcstd alhidd, minutissimd, suh- 

 ovatd, longitmliualitvr costatis, costis distantibus, 

 inrisi-i, in medio anfractimm costis spiralihm Irilms 

 der„s,ati.<, infersfi/ii.< exrara/is ; anfractih,,, 

 ,inat,n,r. infrahia „,,nlali., .,1 unl pr.,f,o.d.l ^ a,.er- 

 tin-.; s„l,n,l,n,d,;, ,uar,ji,ie a,-„t„. 



The NiirAHLB Rissoa. Shell whitish, very small, 

 somewhat ovate, longitudinally ribbed, ribs 

 distant, incised, decussated by three spiral ribs 

 in the middle of each whorl ; interstices exca- 

 vated ; whorls four, biangular below, suture 

 deep; aperture rather round, margin sharp. 



Jeffreys. Sowerby's Illustrated Index of Brit. Sp. 



Chemnitzia Barleei, Clark. 



Ilab. Britain. 



Species 53. (Mus. Sowerby.) 



Rissoa nitida. Ei.<. (Eissoina) testd albd, solidd, ekitd 



Spird elongatd, widiu siihinllati'^ (i/u'rr in-injiiiiatu 



anfraciihus ocI<k n. „,-,,■;.-.■, s/.u^ililrr rl l,.H,j,tiuU 



naliter costatis, costi:i ad amjiilnr; ii<idnsi.< -^ a^ieiiiin 



