Mr. Forbes on new British Mollusca. 107 



tennularia indivisa, dredged in deep water off the coast of 

 Ballaugh, Isle of Man, September 30, 1839. 



V. RissoA RUPESTRis. Nov. Sp. Forbcs. Plate II. fig. 13. 



R. testd ohlongo-turritdy albd, anfractibus 7 planulatis, ultimo 



basi striato ; suturis marginatis ; labro simplici. Lon. 



Oy*^ unc. 



Shell translucent, white, with seven flat whorls, which are 

 almost smooth ; round the summit of each runs a spiral stria, 

 which gives a marginated appearance to the suture. The 

 basal whorl is slightly carinated and spirally striated below 

 the carination; a few obsolete striaj sometimes appear above : 

 the mouth is pear-shaped, and has no rib thickening the outer 

 lip ; the pillar lip is broad, and slightly folded back. Animal 

 milk-white. 



This Rissoa is found in crevices of rocks at half-tide along 

 with Rissoa dngilla (to which it is nearly allied), KeUia rubra, 

 and Auricula alba, at Kirk Santon Head, Isle of Man. 



VI. Pleurotoma Smithii. Nov. Sp. Forbes. Plate II. 

 fig. 14. 



P. testd fusiformi-turritd, sub lente tenuissime striata ; an- 

 fractibus 8 convesciusculis, costatis, costis 12 ; aperturd ob- 

 longo-lanceolatd, spird multu breviore, caudd brevi. Lon. 

 O/o unc. 



This pretty species has the whorls slightly rounded, and 

 ornamented with strong longitudinal ribs, which ai'e not, 

 however, continuous from whorl to whorl. The whorls are 

 slightly angulated at their summits : the sutures are deep. 

 Its colour is yellowish white, with numerous spiral bands of 

 yellowish brown, which give it a very elegant appearance. 

 The mouth is oblong, and the outer lip is thickened by a rib. 

 The canal is short and slightly inclined to the left. I have 

 dedicated it to James Smith, Esq., of Jordanhill, by whom 

 it was dredged in July last in Lamlash Bay, Arran. 



VII. Pleurotoma coarctata. Nov. Sp. Forbes. Plate 

 II. fig. 15. 



P. testd anguste fusiformi, striatd, anfractibus 7 convexiuscu- 



I 2 



