﻿P T E R P D A. 



hval-Ea. 



Spccios 8. (Fig. II, b, Mus. Sowerby.) 

 Hyal.ea outusa. Hija. testa inirvd, temiissimd, iial- 

 liJis.<iine .•iKccinea, hijalind; disco ventrali hrevi, 

 ml undo ; spinis Meralibus brevibus, duplicatis, 

 a/iio- ceiitrali tnmcato, iitrinque vlx derdato, aper- 

 turd trUjond, labro prodwclo. 

 The iiiiTu.sK Htaljia. Shell small, very thin, very 

 p;ilo amber, glassy ; ventral disc short, rounded ; 

 latei-al spines short, double, central apex trun- 

 cated ; just perceptibly dentated on each side ; 

 ai-ierture trigonal, outer lip produced. 

 S.)WKi;r.v. 



]{„n. ? 



The side appendages are smaller, and the bifid ] 

 denticles more obtnse than in Hi/alina him/irostriK, i 

 and tlie central apex broader and more truncated. 



diu'to, tfuiicalo; aperturd augustd, munjiiie siin- 

 pUci, refexo. 

 The intermediate Htal.ea. Shell small, broad, 

 white, pellucid, posteriorly rather compressed, 

 with four teeth ; lateral teeth trigonal, acute, 

 teeth at the apex small, acuminated ; central 

 apex rather produced, truncated ; aperture nar- 

 row, margin simple, reflected. 

 Sowerby. 



Hub. y 



Larger, more compressed at the sides, and less 

 globose than //. inintUa. Smaller, and more con- 

 tracted anteriorly than H. qiuulridentata. 



Species 9. (Mus. Sowerby.) 

 HvAL.t'.A minuta. Tlija. testa minutissimd, globosd, sub- 



ruirrrd. f.n.-tn-r ,(,^;/»^■^.(^^ ;.)v«;.',s-.s-(7/»,- Interalibus 

 mi„„t:' iiin,t,-,it,ili^, iipicr O'lilnill prijdndo, late 

 trinii-atn^ iitn'injKr iiiiniifistiiine uiitdoitato ; aper- 

 turd aiKjHsti: semiluiiari ; marglne simpUci, rcjiexo. 



The minute Hyal.s:a. Shell very minute, globose, 

 rather ashy, posteriorly narrowed, lateral pro- 

 cesses with a minute tooth, central apex produced, 

 broadly truncate, with a single very minute 

 tooth on each side ; aperture narrowly semilunar, 

 with a simple reflex margin. 



Sowehuy. 



Hah. ? 



Species 10. (Mus. Sowerby.) 



Hyal.ba intekmedia. Rija. testa parud,, lata, alb,!, 



pellucidd, postlcu subcompressd, quadrideiifafd, den- 



tibus lateralibu-t trigonis, acutU, dentibiis ad 



apicem parvis, acumiiuitis ; apice ceutrali snbpra- 



Species 11. (Fig. a, b, Mus. Brit.) 



Hyal^a LIMBAta. Hi/a. testa pallidelilacindvel fused, 

 triguild, disco ventrali tuuiidfi, femiiliu- Viraln. aja're 



angusth subtruncato, prt y.<il,ii.^ hilrrahlmx ahiH<, 



trigonis, aciiininatis, acute frid,'„lalis ; nivrtiird 

 subtrigond, Idbio interno anguste refle.ro ; labro 

 longe prod%icto, leviter elevaio, rostrato ; rostro ad 

 terminiim bilobato; margine medio subeoiitracto. 



The bordered Htalina. Shell pale lilac or brown, 

 trigonal, ventral disc tumid, finely ridged, apex 

 narrowly rather truncated, lateral processes 

 winged, trigonal, acuminated, sharply triden- 

 tate; aperture subtrigonal ; inner lip narrowly 

 reflected ; outer lip much produced, slightly 

 elevated, beaked, slightly contracted in the 

 middle. 



D'Orbigny. Voy. Amer. Merid. PL VI. f. 11, 15. 



Hab. Atlantic Ocean. 



Species 12. (Fig. a, b, Mus. Brit.) 

 Hyal^a longirostris. Eya. testa fused, eel alba, 

 versus aperturam fusco suffusd, disco ventrali 

 tumido, rotundo, tenuiter lirato, apice anguste sub- 

 iruneatu, processibus lateralihus alatis, trigonis, 

 bidentatis ; aperturd subtrigond, labia interno 



