126 TELLINULE. 



size, smooth on the outer surfaces, and on the inner striated 

 with about thirty of the delicate vessels of the branchial circu- 

 lation ; the corresponding pair's of subtriangular palpi are also 

 pale brown, smooth on the outside, except showing a longi- 

 tudinal furrow, and pectinated within. 



These beautiful shells are frequently taken alive in the 

 coralline zone at Exmouth. This animal may be placed, par 

 excellence, at the head of the typical species. 



T. CRASSA, Montagu. 

 T. crassa, Brit. Moll. i. p. 288, pi. 20. f. 1, 2. 



Animal suborbicular, lentiform ; the general ground colour 

 is pale drab; mantle quite open, double-edged, finely, closely 

 and conspicuously fringed, produced posteriorly into two long 

 rather slender siphons, separate from their bases, the branchial 

 quite plain at its termination ; the upper or anal one, which 

 is apparently rather the largest in diameter, and capable of 

 great inflation, has six triangular points at the orifice ; their 

 ground colour is marked with two or tliree intenser whitish 

 longitudinal lines. I am unable to state how far the tubes 

 can be extended, as the animal was sent to Bath in 1851, 

 wrapped in moist sea- weed, accompanied by bottles of sea- 

 water, and had become partially collapsed; but I should 

 think, judging from other Tellina, that in the specimen exa- 

 mined they would, when fully exserted, be at least 2 inches 

 long. The shell was the largest I had ever seen, measuring 

 transversely 2|, and vertically 2g inches. The foot is the 

 usual large, spatulate, thick, muscular, linguiform appendage 

 of the TeUina, perfectly simple, without a trace of a groove in 

 the heel. The pair of branchiae on each side are subcircular, 

 of very thin texture, the lower of great extent, the upper not 

 half the depth of its larger fellow ; both coarsely but not 

 distinctly pectinated. The palpi, a pair on each side, are nar- 

 row, slender, pointed, of a very elongated triangular shape, 

 quite smooth externally, but well striated within. The liver 

 is anterior, of a dark brownish-green ; the stomach contained 

 the usual tricuspid membrane, or attritor, and the crystalline 

 stylet of large size. The heart, auricles, nervous ganglia, with 



