﻿P T E E P D A. 



/n'AL.KA. ItlACniA. ATLASTA. 

 Species 15. (Fig. «,, /;, Mns. Brit.) 



Hv.\L.F,A (Diacria) trispinosa. Hija. testa compressd, 

 ti'inii.^siiiid, alba, fiisco iii' pnrtihus stiffusd, ohliqiw 

 .■<nhi]imiU;it'K fn'spi)iosd; spinislateralihus brevibus, 

 iii-ntir^, iitriin/ii,' ad angulnin. dispositis ; spina 

 a/iii-iili ,'lnii'i,ilit. iitfrviiald, acuminata; disco ven- 

 li-nli roitr<\r,i, ,lif:,-,> ihirmli transverse lirato, tri- 

 lohiifij : (ipriiiirti iniiiiif:td, iTMrginibiis subreflexis. 



The tiikke-simned Hyal.ea. Shell compressed, very 

 thin, white, suffused with brown in parts, 

 obli(|uo. rather square, three spined; lateral 

 spines shurl, sharp, placed at the angle on each 

 side, apical spine elongated, attenuated, acu- 

 minated ; ventral disc convex, dorsal disc 

 transversely ridged, trilobate ; aperture narrow, 

 margins somewhat reflected. 



LESi-Eru. D'Orl.igny, Voy. Amer. Merid. PI. VII. 

 f. l-.^. 



H.ih. Atlantic Ocuau. 



Species 17. (Fig. ". '', Mus. Sowerby.) 



Hyalju inflexa (Diacria). Hya. testii parod, albii 

 subtriyond, trispinusd, spinis lateralibws deratis 

 brevibus; spina apicali produetd, miriitatd 

 apertnrn a^qne ml spinas Jaterahs inrlsd, laliiis 



.■lie. 



hihn, vroilnrlu 



culd, lahio i. ^ ^ 



hbato. 



The inbent Hyal-BA. Shell small, white, subtrigonal, 

 three-spined ; lateral spines raised, short ; apical 

 spine produced, hooked ; aperture slit as far as 

 the lateral spines, rather broad ; inner lip re- 

 flected, outer lip produced, margin lobed. 



Lesuedr. D'Orbigny, Voy. Amer. Merid. PI. TX. 

 f. lC-20. 



Hah. Atlantic Ocean. 



Species ICi. fFig. a. h. Mns. Brit.) 



Hvalj:a (Diacria) muckonata. Ilya. tivtd hiid. cmti- 

 prrssd, alhd, fusco prope aperturnin jiirld. lute 

 sulxjuadrald, trispinosa; spinis ItilmilUms re- 

 motis, alatis. depri'ssi^, spina apiruli hitiii raid, 

 },ri'rii'sruh! : ilinco ventrali fere la'vigato, disco 

 dn,:<iili /ii//<(/'i, ralide riigalo ; apertiird angustd, 

 lahiis rejie.ris, fiiseis, aiigustis. 



The sharp- pointed Hyal.ea. Shell broad, com- 

 pressed, white, painted with brown near the 

 ajierture, broadly subquadrate, three-spiueil ; 

 lateral spines remote, winged, depressed ; apical 

 spine rather wide, rather short, frequently trun- 

 cated ; ventral disc nearly smooth, dorsal disc 

 lobed, strongly wrinkled ; aperture narrow, lips 

 reflected, brown, narrow. 



Lesueur. D'Orbigny, Voy. Amer. Merid. PI. VII. 

 f. 6-10. 



Hah. Atlantic Ocean. 



With broader disc and wider ala- than in Hyatea 



trispinosa. The apical spine is also broader and 



Species 18. (Fig. a, b, Mns. Brit.) 



Hyal^A LABIATA (Diacria). Sya. testa alhd, ehyinialn. 

 subtrigond, trispinosa, siihromprfs<:d : dim-i' durxnli 

 antice producto, angusti' aisfnitn. mrJin inn/iiliitn : 

 disco ventrali convexo, kevigatu. sjiiiiis luli-rnliliiin 

 retror&is, acuiis, spind apicali hreriihcnld, drflrrd. 

 uiicinatd ; aperturd trigond, labro pnnhirfo, 

 angulnto, labia interno elevatim refiexo. 



The lipped Hyal«a. Shell white, elongated, sub- 

 trigonal, three-spined, subcompressed ; dorsal 

 disc produced anteriorly, narrowly beaked, with 

 a central angle; ventral disc convex, smooth, 

 lateral spines turned backwards, sharp, apical 

 spine rather short, bent downwards, hooked ; 

 aperture three-cornered, outer lip produced, an- 

 gular, inner lip raised or reflected. 



D'Orbigny. Voy. Amer. Merid. PI. VI. f 21-2.V 



Bab. Atlantic Ocean. 



pecies 19. (Fig. a, b, Mus.- 



Copied.) 



IAL.EA DEPRESSA (Diacria). Hya. testa miniUd, 

 alhd, suhtrigon.d, compressd, processibus lateralibm 

 ad rimavi apertures projectis ; aperatwd profumie 

 semilunari, simpliei; labro producto, lahio interno 

 leviter elevato, apice longe producto ad lermimnn 

 acuminate, uncinato. 



