Lrj/lhrcpiin MoUuacan Fauni. U')'i 



D. spinnnua, Clieiii., itself a delicat<'.ly clia.se*! liltio slr*II, 

 takes secojid rank without doubt ; D. oheswi, d'()rl)., a fiimly 

 decussate species, is alsi) eclipsed ; D. scmisulcatuSy Ilauley, 

 from the Indian Ocean, posteriorly similar in its scul|)ture, 

 is anteriorly almost plain, the whole of the surface of our 

 species bein<^ closely ribbed and spirally sharply sulcate, 

 which gives a clear-cut character to the sculpture. The 

 ventral margin is beautifully multi denticulate. Posteriorly, 

 when the two closed valves are viiiwed laterally, the double 

 row of long spined convergent ribs, witli the inner ranks of 

 costa; armed wiih shorter spines, form a beautiful heart-shaped 

 surface, recalling Cardium {Ctenocardia) ht/stri.t, Wood, in 

 miniature. Indeed, after a minute comparison of the other 

 species of the genus, to some of which allusion has just been 

 made, D. clathratua, Desh. 1859 (cf. Reeve, Conch. Icon., 

 DoiiaXj t. 57), perhaps is the nearest ally; but the character 

 of the decussating sculpture is seen, with a lens, to be of 

 a different character, and it is more isosceles- shaped than our 

 new form. 



Cumingia occalillu*, sp. n. (PI. IX. ligs. 7, 7a.) 



C. testa infequibitcrali, protea, ovato-oblonga vel fere rotunda, 

 hie postice abhrcviata, illic subquadrata, alba, delicata ; um- 

 bonihus baud prominulis, contiguis, obliquatis, superficio 

 omni concentrice teuui-laniellata, lanicUis marginem apud von- 

 tralem saepius condensatis, irrogularibu.-*, in medio regularitor 

 dispositis, interstitiis loiigitudinaliter delicatis.^imo et arete 

 striatis, spccirainibus vetustis sa?pe cvanidis, postice compressis, 

 intus pagina alba, nitida, niargine aiitico .simul ac ventrali pallide 

 puniceo hie illic variegate, einu palliali ad medium asceudeiite, 

 lif^araoiito intorno, valvis nnibabus dento uno cardinali, simul ac 

 fossa elongata, oblicjuc cochleari, pneditis, in doxtra quoque 

 duobus dentil)us lateralibus fortiter instructu. 



Alt. 14, lat. 1<'>, diam. lO mm. (sp. max.). 



This niollusk doubtless, in common with many otlu-r />»-/>- 

 tomf/(Vj Thyelhr, and Cniniivjia', inhabits sponges and corals; 

 hence the inequality of form, as protean indeed as any British 

 Soxicava. The delicate sculpture is almost identical vvith 

 that of Thijella lamclloaa, A. Ad., but the hinge, with un- 

 doubted laterals in the right valve, seems more akin to 

 Cuminqia than to I.ejitomyn, with which genus I had 

 es-^ayed at first to connect it. 



The large ligamentary pit is obliquely elongate and spoon- 

 sliaped, most resembling that of Jjeptomya. An interesting 



♦ Uccutus, harrowed ; from the lumellateJ parullfl riilges. 



38* 



