N U C U L A. 



Genus NUCUTLA, Lamakits. 

 TesUx bivcdvis, biimcsculosa, plus miaiisve ovato- 

 trkjona, ulrinqiie plerumqae ela2isa, epidermule 

 imliUA; latere poatico breviore, upidhus versus 

 lateram podicum imlinalh ; inius margarikwed, 

 irtargine cardinali dentibus nwmrosis acutis ex- 

 stantibm seriatim depositis uirinqm arinatd ; 

 ligametitum externum nuUma. (JartiUigo elastica 

 infoveam medianum deposita. 

 Shell bivalve, bimuscular, more or loss ovately tri- 

 angular, generally closed at botli ends, covered 

 with an epidermis; posterior side shorter, with 

 apices turned towards the posterior side; pearly 

 within, the hinge margin armed with numerous 

 sharp out standing teeth plaee.l in a row on each 

 side; no external pit. An ela-^tir cartilage placed 

 in a central pit. 

 The thirty-three species included in tin' genus 

 restricted as above, form a very fairly cirrvunscribed 

 group. The shortness of the posterior side towards 

 which the apex turns in all the species, and the closed, 

 or nearly closed margins, together with the general 

 appearance, make every Nucula distinguishable at a 

 glance from Loedce, YokUa;, &c. The geographical range of 

 true Nuculce is perhaps wider than that of other genera 

 of the same family. Our own seas produce five, of 

 which several are also tenants of the Mediterranean 

 and iEgean Seas. One or two reach the Arctic circle, 

 while several others extend southwards to our anti- 

 podes. China and Japan in tlie east balance N. America 

 in the west : each contributes its quota to the little 

 group. ^ 



Species 1. (Mus. Ci 



Brit.) 



Nucula co.nve.xa. Nw:. iestd ohUqni ovatd, sohdd, 

 IfBvigatd, convexd, /,dvd, cmndeo palUdi fasciatd, 

 comentrice obsolete liratd ; latere postlco sub- 

 angulato, subproducto, rotundo ; latere antic, 

 oblique irroducto, mar.jine dorsali convexo, margme 

 ventraliantice convexo; apicibi's rotundi.^, epuler- 

 mide ignotd. 



F.-bru; 



The con-vex Nucula. Shell oblicjuely ovate, .solid, 

 smooth, convex, fulvous, lightly banded with blue, 

 concentrically obsoletely ridged ; posterior side 

 subangular, a little produced, rounded; anterior 

 side obliquely produced, dorsal margin convex, 

 ventral margin anteriorly convex ; apices rounded ; 

 epidermis unknown. 



SowEUBY. Cone. lUust, f. 2, Thes. Cone. llanU-y on 

 Nucula, p. 28. 



Hah. China (Straits of Malacca). 



A smooth, full shell, only known by specimen.^ tr...ni 



which the epidermis has been removed. 



Species 2. (Mus. Sowerby.) 



Nucula nucleus. Nuc. tedd trigond, subetevatd, sub- 

 Icevigatd, obscure teiiaissime striata et ad margines 

 laterales concentrice liratd, subventricosd, solidd ; 

 latere 2}ostico brevi, subp^pendiculari, angulato ; 

 latere antico acuminatim producto, margine dor- 

 sali declivi. Intas margine veutrali crenato. 



The nut Nucul.\. Shell trigonal, subelevated, rather 

 smooth, obscurely very finely striated and concen- 

 trically lirated at the lateral margins, rather 

 ventricose, solid; posterior side short, rather 

 perpendicular, angulated ; anterior side acumi- 

 nately produced, dorsal margin sloped. Ventral 

 margin crenulated within. 



LiNN^us (Area), Systema Naturae. 



Glycimeris argeiUcea, Da Costa. 



Nucula Margaritacea,, Lamarck. 



Hab. British and European Seas. 



Species 3. (Mus. Sowerby, &c.) 

 Nucula decussata. Nuc. tesid, solidd, ti-igond, elevatd, 

 subcompressd, rugis concentricis et sfriis radian- 

 tihis decussatd ; margine ventrali crasse crenato ; 

 lumdd -niagnd, convexd, medix) Icevigatd, margme 

 corrugato ; apicibus elevatis, subacuminatis, lateri- 

 bus declivis. 



