IIEPOKT ON THE LAMELUBRANCHIATA. 269 



Arm {Macrodon) dalli, ii. sp. (PI. XVII. fig. 10-106). 



Testa transversa, oblonga, vakle insequilateralis, antiee rotundata, postice obliquiter 

 arcuatim truncata, ad extremitatem acute rotundata, sordide alljida, epidermide fusco- 

 olivacea concentrice lamellata induta. Valvse mediocriter tenues, undique tenuiter liratae, 

 incrementique lineis sculptte. Pagina interna caeruleo-allnda, nitida, tenuiter radiatim 

 striata, margine externo vix crenulato. Area ligamenti angustis.sima, linearis. Linea 

 cardinalis dentibus paucis (circiter 8-10) infequalibus anticis, duobus posticis perelongatis, 

 margine dorsali piarallelis, instructa. 



This species is very inequilateral, oblong, transverse, moderately convex, rounded in 

 front, obliquely curvedly truncate behind, and sharply rounded at the extremity. The 

 valves are not particularly thick, Ijut rather thin, dirty whitish, and covered to a great 

 extent with a brownish-olive epidermis which at short intervals is concentrically lamellated. 

 The sculpture consists of fine close-set radiating lirse and fine Hues of growth, some at 

 intervals, which mark the position of the epidermal lamella3, being especially conspicuous, 

 'i'he umbones are small, close together, not more than a millimetre apart, and situated at 

 scarcely a fourth of the whole length from the anterior end. The ligamental area is very 

 narrow indeed, the ligament being principally behind the Ijeaks in a groove on the hinge- 

 niargin. There are eight or ten denticles upon the anterior half of the hinge-plate, of which 

 the front ones are the largest, and at the posterior end are two or three elongated ones 

 parallel with the dorsal outline. The interior is bluish-white, exhibiting concentric zones 

 and radiating fine but distinct strise, except on the margin outside the pallial line. 



Length 31 mm., height 18, diameter 12. 



Habitat. — Station 233a, off Kobe, Japan, in 50 fathoms ; sand. 



The posterior teeth are not so long as in the type of the section Macrodon, but still 

 quite diflerent from any other species of recent Arcidaj with which I am acquamted. 



It is interesting to find this fossil form occurring in the Pacific Ocean, it having 

 already been recorded from deep water in the West Atlantic by Mr. Dall (Eeport Moll. 

 "Blake" Exped., 1877-79, p. 120), with whose name I have the pleasure of associating 

 the present species. 



Family J r l 1 1 d m. 



Julia, Gould. 

 Julia exquisita, Gould. 



Julia exquisita, Gould, rroc. Boston Soc Xat. Hist. (1862), vol viii. p. 284. 

 Julia exquisita, Gould, Otia Conch., p. 241. 



Julia exquisita, 0. Semper, Journ. de Conch., 1865, vol xiii. p. 297. 



Prasina horhonica, Deshayes (1863), in ^Maillard's llr .!.• hi liruniuii, vol. ii. Annexe E, p. 29, 

 pi. iv. tigs. 4-8. 

 Te.sta minuta, oblonga, antiee producta, rostrata, autc umbones concave depressa, 



