108 THE VOYAGE OF H.M.S. CHALLENGED. 



irregularibus aut pallidis vel sanguineis picta. Margo dorsi aiiticiis elongatus, liorizou- 

 talis, rectiusculus, posticus brevior, abrupte descendens, vix arcuatiis ; margo ventralis 

 dorsali anteriori subparallelus, antice adscendeus, postice interdum subsiuuatus. Umbones 

 aeuti, j^rominentes, postmediani. Dentes cardinales inajquales, duo in utraque valva, 

 laterales in utroque latere, cardinaliljus baud renioti. Ligamentum externum breve, in 

 fossa parva situm. Cartilage interna angusta, obliqua, postice inclinata. Sinus pallii 

 profundissimus, cicatricem anteriorem fere attingens. 



This species is nearly twice as long as high, rather compressed, of an oblong form, 

 rounded anteriorly, narrowed and subacuminate behind. It is very inequilateral, thickish, 

 either of a pale salmon tint marked with irregular sanguineous spots and streaks, or 

 ojiaque white varied with similar markings of a pale semipellucid character. The front 

 dorsal margin is almost horizontal, faintly concave close to the umbones, then straightish 

 or very slightly excurved. The posterior is much shorter, a very little arched, especially 

 at the upper \)avt, and considerably oblique, forming at the extremity with the lower 

 outline a sharpish angle which is most conspicuous in the left valve. The ventral out- 

 line is rather straight at the middle, exhibiting the slightest indication of a sinuation 

 towards the hinder end, being considerably upcurved in front. The umbones are small, 

 acute, and a little produced. The hinge consists of two cardinal teeth and two laterals 

 in each valve, mth an internal and an external ligament. The cardinals in the right 

 valve are divergent from one another, with a triangular pit between them, the posterior, 

 being stouter than the other and somewhat cleft at the top. In the left valve the 

 anterior is the stronger tooth and also somewhat bifid, the hinder one being thin, 

 lamellar, and bordering the internal ligament. The lateral teeth are subequidistant and 

 well developed. The external ligament is situated in a short sunken area behind the 

 beaks, and consequently is very little if at all elevated aliove the margin. The internal 

 cartilage is narrow, olilique, and posterior to the cardinal teeth. The pallia! sinus is ver^" 

 deep, extending almost to the anterior muscular impression. 



Length 10 mm., height 5-j, diameter 2-^. 



Habitat. — Levuka, Fiji Islands, in 12 fathoms (Challenger); Island of Ngau, Fiji, 

 at a depth of 10 fathoms on a sandy bottom (British Museum) ; Lord Hood's Island, in 

 coral sand at low water (Cuming). 



The elongate form of this species was probably the cause which induced Mr. Sowerby 

 to locate it in the genus .Tellina, but it might with equal propriety be included in 

 Semele. 



Tellina diluta, n. sp. (PI. IV. figs. 7-71). 



Testa oblonga, postice angustata et subacuminata, antice acute rotundata, valde 

 inasquilateralis, tenuis, nitida, alba aut flavescens, concentrice tenuissime striata, medio- 



