REPORT ON THE LAMELLIBRANCHIATA. 97 



Wliydali on the west coast of Africa. I am inclined to consider the former " habitat " 

 incorrect, for there is little likelihood of West Africa and South Australia producing the 

 same species. There is no doubt regarding the correctness of the locality Whydah, for 

 the specimens of this species referred to were dredged by Captain Knocker together with 

 a number of others, all of which are West African types. 



The present species has a more triangular appearance, is a little narrower, rather more 

 acuminate at both ends, and lacks the broad reddish ray near the umbones. The 

 posterior dorsal slope is longer and a trifle more oblique, so that the apical angle is also 

 somewhat more acute. 



Tellina {Macoma) uruguayensis, n. sp. (PI. IV. figs. 5-56). 



Testa tenuis, insequilateralis, transversim elongata, utrinque hians, postice angustata, 

 subrostrata, dextrorsum conspicue flexa, antice rotundata, parum ineequivalvis, alba, 

 epidermide lutescenti prope marginem induta, striis incrementi tenuibus insculpta. 

 Margo dorsi anticus elongatus, vix descendens, leviter arcuatus, posticus brevior, prope 

 umbones paulo concavus dein, rectus, valde declivis. Ventris margo lente curvatus, 

 postice in valva sinistra levi.ssime sinuosus. Dentes cardinales valvse dextraj duo, parvi, 

 in valva sinistra unicus. Pallii sinus profundus, ad finem rotundatus. Pagina interna 

 alba, aliquanto iridescens, radiatim substriata. 



This species is very much longer than high, thin, white, finely striated by lines of 

 growth, and more or less covered near the ventral margin Ijy a dirty yellowish epidermis. 

 It is considerably inequilateral, the anterior side laeing the larger, rounded at the extre- 

 mity, and scarcely narrowing ; the hinder portion, on the contrary, is considerably 

 attenuated or subrostrate, and narrowly truncated at the extremity. The valves are a 

 little unequal, the left being rather more convex than the other. Both are turned 

 conspicuously to the right at the hinder end, and gape somewhat on both sides. The 

 front dorsal outline is faintly arcuate and only a very little oblique. The posterior, 

 which is shorter, being much more sloping, at first, close to the beaks a little concave and 

 then almost rectilinear. The lower margin is but very slightly arched near the middle, 

 rises in a gentle curve anteriorly, and behind exhibits in the right valve a very faint 

 trace of an incurvation or sinus. The ligament is sordid yellow, short and prominent. 

 The hinge is composed of two small prominent teeth in the right valve and a single one 

 in the left. The inner surface of the valves is white, somewhat iridescent and radiately 

 substriated. The anterior muscular scar is elongate and irregular in outline, the posterior 

 is shorter and broader. The siphonal inflection is ver)^ deep, narrow, rounded at the 

 extremity, the line which encloses it returning about half way across the valves before 

 joining the other part of the pallial line, parallel with the ventral margin. 



Length 22 mm., height 12^, diameter 6. 



Habitat. — Station 321, off" Monte Video, Uruguay, in 13 fathoms; mud. 



(ZOOL. CHALL. EXP. — PART XXXV. 188.").) Mill 1.3 



