REPORT ON THE LAMELLIBRANCHIATA. 281 



This species is remarkable for the iridescent gloss of the exterior, its elougato fonn, 

 well-developed hiuge-tceth, and the distinct internal ligament. 



Myrina, H. and A. Adams. 



Myrina coppingeri, u. sp. (PI. XVI. figs. 9-9Z>). 



Testa oblonga, antice augustata, valde insequilateralis, epidermide viridi-flavescente 

 induta, concentrice tenuiter striata. Margo dorsi posticus elongatus, rectus, paulo sursum 

 inclinatus, ventralis rectiusculus, vel in medio vix sinuatus. Linea cardinalis crassiuscula, 

 transvcrsim striata, in medio ligamento fere omnino interno interrupta. Pagina interna 

 ceeruleo-albida, iridescens. 



This species is oblong, convex, about twice as long as high, considerably narrower at 

 the anterior end than behind. It is moderately strong, covered with a greenish-yellow 

 epidermis, and finely concentrically striated. The posterior dorsal margin gradually 

 ascends from the umbones, and is rectilinear, the ventral outline being also straightish, 

 but very slightly incurved at the middle. The umbones incline over towards the front, 

 and are situated at about one-sixth of the entire length from the anterior extremity. 

 The hiuge-liue is rather strong, striated across at both ends, and interrupted at the 

 middle by the brown ligament, which is internal and scarcely at all visible externally. 

 The interior is bluish-white, a little glossy and iridescent. 



Length 9 mm., height 4f, diameter 3|. 



Habitat. — Station 184, east of Cape York, North Australia, in 1400 fathoms ; 

 Globio-erina ooze. 



O 



This differs from the only known species of the genus in having the hinge-line finely 

 striated across on each side the ligament. Idas of Jeffreys has the hinge-plate similarly 

 crenated, but the ligament is described as external. 



Idas, Jefi"reys. 



Idas dalli, n. sp. (PI. XVI. figs. 10-10&). 



Testa elongata, obliqua, parva, pellucida, nitida, iusigniter inaequilateralis, tenuissima, 

 modioliformis. Linea cardinalis bre^'is, recta ; latera obliqua, posticum leviter arcuatum, 

 anticum longius, in medio incurvatum. L^mbones parvi, acuti, parum prominentes, ante 

 medium linea; cardinalis denticulata) coUocati. 



This little species is very narrow and elongate, thin, semitransparent, white, glossy, 

 almost destitute of sculpture, exhibiting only traces of fine lines of growth. It is oblique 

 in regard to the straight hinge-margin, the hinder side being slightly excurved, and the 

 anterior a little sinuate at the middle, the sinus marking a faint depression which 

 radiates from the umbones down both valves. The beaks are small, a little prominent 



(ZOOL. CHALL. EXP. — PART XXXV. — 1885.) Mm 36 



