REPORT ON THE LAMELLIBRANCHIATA. 41 



larger shell than Necera rostrata, Spengler, although very similarly sculptured, and 

 terminates in a much shorter posterior rostrum. 



Neceixi consociata, n. sp. (PI. IX. figs. 7~7b). 



Testa parva, tenuis, pellucida, globosa, postice subito rostrata ; rostrum breve, 

 truncatum, increment! lineis subvalidis sculptum, carina obliqua distincta dimidiatum. 

 Valvse antice rotundatse, inferne late arcuatje, postice prope carinam subprofunde sinuatae, 

 lamellis brevibus paucis (circa decern) ornatse. Umbones Iseves, leviter prominentes, 

 antemediani, fere in ^ longitudinis collocati. Cardo in valva sinistra edentulus, in 

 dextra ? Fossa ligament! linearis, margine dorsali parallela, baud intus projecta. 



This species must approach very closely Necera lamelUfera of Dall, and may indeed 

 prove eventually to be the young state or a variety of it. It may, however, be at once 

 distinguished from that species, which is only known to me by description, by the 

 distinct keel, which, starting from the lower corner of the rostrum, curves up obliquely 

 towards, but does not extend quite to, the umbones. The latter, too, are apparently 

 placed more forward, being just a shade more than one-third of the total length from the 

 anterior end, whilst in Necera lamelUfera they appear to be very little in advance of the 

 centre. Both species are similarly sculptured with fine concentric lamellae, and there is 

 probably not much difference in the ligamentary fossette. The freshest valve procured is 

 thin, glassy, and subtransparent, and, on examination under the microscope, presents a 

 minutely punctate surface towards the umbo, both within and without. 



Length 4^ mm., height 3, approximate diameter 2^^. 



Habitat. — Station 24, off Culebra Island, West Indies, in 390 fathoms, Pteropod 

 ooze; and Station 33, off Bermuda, in 435 fathoms, coral mud. 



Necera azorica, n. sp. (PI. X. figs. 7-7h). 



Testa tenuis, inajquilateralis, ovata, supernc recta, vix rostrata, mediocriter couvexa, 

 hand nitida, rugis concentricis miuutis irregularibus postice subito obliquis ornata. 

 Margo dorsi fere rectus, antice leviter curvatus. Latus anticum breve, rotundatum, 

 posticum longius, rostro brevissimo, impressione baud profundo ab umbone radiant! 

 signato, terminatum. Ventris margo late arcuatus, postice ad impressionem levissime 

 sinuatum. Umbones parvi, parum prominentes, nucleo uitente obtuso instructi, ante 

 medium collocati. Ligamentum minutum, obliquum. 



Only a single left valve is at present known of this species. It is small, thin, 

 rather inequilateral, irregularly ovate, having the upper margin nearly straight and the 

 posterior end only a very little beaked. It is semitransparent-white, moderately convex, 



(ZOOL. CHALL. EXP. PART XXXV. — 1885.) Mm 6 



