Mr. J. Gwyn Jeffreys on a new Species of Rissoa. 435 



15. Nematogenys palliduSf Ph. 



This species also corresponds with N. inermis in size, form, 

 and number of the fin-rays ; but, whilst in the latter species the 

 skin of the belly is quite smooth, in N. pallidus it is as thickly 

 and conspicuously beset Avith papilhie as the back, lips, &c.; and 

 the coloration is very different, viz. a bright brownish red, 

 almost a flesh-colour : it is only on the head also that any 

 darker spots are to be distinguished, and they are here, more- 

 over, but ill defined. Scarcely any darker cross markings are to 

 be seen on the dorsal and caudal fins ; the other fins are perfectly 

 white. The barbels do not reach to the origin of the pectoral. 



LXIV. — Description of a neiv Species 0/ Rissoa /rom Madeira, 

 By J. Gwyn Jeffkkys, F.R.S. 



The Rev. R. B. Watson has kindly sent me specimens of a 

 Rissoa, found by him at ]\Iadeira, which appears to be unde- 

 scribed j and, at his request, I will now record the discovery. 



Rissoa picta. 

 Shell conic-oval, rather solid, semitransparent, and glossy : 

 sculpture, numerous (although not close-set) slight, equal- sized, 

 spiral strise, which cover the body-whorl, but are not discerni- 

 ble on the upper whorls ; there is no labial rib : colour pale 

 yellowish-white, variegated by equidistant rows of oblong 

 reddish-brown spots; the body-whorl has three rows (the 

 lower two being sometimes partially confluent), and each of 

 the upper three whorls has tw^o rows : spire rather short, 

 bluntly pointed : whorls five and a half, somewhat compressed, 

 encircled below^ the suture by a thickened rim, owing to the 

 last-formed whorl overlapping the preceding one in that part; 

 the body-whorl occupies about two-thirds of the shell : suture 

 slight ; mouth roundish oval, not expanded : outer lip sharp : 

 ijiner lip reflected on the pillar and base, united above with 

 the outer lip : pillar broad and flattened : operculum yellowish, 

 rather thick, nearly smooth ; sj)irc or nucleus small, and 

 placed on the inner side near the base. Length 0'075 in., 

 breadth 0-05. 

 Habitat. Under stones at low-water mark, Madeira (Watson) ; 

 not uncommon. 



The nearest ally to this pretty little shell is R. semistriata, 

 from which it differs not only in the smaller size, but in the 

 whorls being flatter, the sculpture equal and not confined to the 

 upper and lower portions of the body-whorl, and in having three 

 (instead of two) rows of coloured spots on that whorl, and two 

 on each of the preceding whorls. 



