1884.] 'LIGHTNING' AND ' PORCUPINE' EXPEDITIONS. 113 



differs from B. scrobiculata of Moller in being caucellated and in 

 the peculiar sculpture of the apex. 



i/ 6. Rissoa dictyophora, Philippi. 



B. dictyophora, Ph. Moll. Sic. ii. p. 128, t. xxiii. f. 11. 

 'Porcupine' Exp. 1870: Med. St. Benzert Road, Adventure 

 Bank. 



Distribution. Mediterranean and Adriatic ; 40-120 fms. 

 Fossil. Pliocene : Calabria. 



A variety of this species is Alvania weinkauffi of Schwartz v. 

 Mohrenstern. 



/ 7. Rissoa fischeki 1 , Jeffreys. (Plate IX. fig. 1.) 



Shell oval, rather solid, opaque and lustreless: sculpture, 16-18 

 strong longitudinal ribs on the last whorl, 14-16 on the penultimate, 

 10-12 on the next, and merely traces or none at all on the second 

 whorl, the top whorl or apex being smooth ; these ribs are crossed 

 by equallv strong spiral ribs or ridges, of which there are 6-8 on the 

 last whorl, 4 on the penultimate, and 3 on the next whorl, the 

 succeeding or second whorl being marked with a few spiral striae ; 

 the points of intersection are noduled or prickly, but only as to the 

 four upper spiral ridges on the last whorl in consequence of the 

 longitudinal ribs not extending to the lower or basal spiral ridges ; 

 the interstices are oblong : colour pale yellowish or dirty white : 

 spire somewhat tapering : whorls 5, moderately convex, rapidly 

 increasing in size, the last occupying half the spire ; the apex is 

 prominent but twisted : suture deep and angulated : mouth nearly 

 round : outer lip thin, smooth inside : inner lip reflected on the pillar, 

 which is not umbilicated nor perforated. L. 0*1, B. 0'05. 



'Porcupine' Exp. 1870 : Atl. St. 26, 36, Tangier B. 



Distribution. Off Tunis (Nares and 'Shearwater' Exp.); 30- 

 120 fms. 



B. calathus is more slender, and has a longer spire and slighter 

 suture. The present species is somewhat like B. tenuicostata of 

 Seguenza (as described by Grauata) ; but the sculpture is different. 

 In the latter species it is fiuer, and there are fewer longitudinal and 

 spiral ribs or striae, viz. 4 spiral striae on the last or body-whorl, and 



2 on the penultimate and next whorls ; B. fischeri is strongly and 

 regularly cancellated, and it has 6-8 spiral striae on the last whorl, and 



3 or 4 on the penultimate and next whorls. B. etneensis of Aradas 

 and Benoit is only half the size of the present species, and it has 

 closer and more delicate sculpture. B. fischeri differs from B. 

 dictyophora var. weinkauffi in the same respects as it does from B. 

 tenuicostata, as well as in having a shorter spire and a proportionally 

 larger body-whorl. It is also allied to jB. zetlandica ; but that species 

 is of a more oblique shape, it has not the tuberous and cancellated 

 sculpture of B. fischeri, the outer lip is expanded, and the spiral 

 striae at the base are fewer and stronger. B. clathrata is a larger 



1 Named in honour of Dr. Paul Fischer, -whose concholos;ical labours and 

 especially his excellent 'Manuel de Oonchyliologie' are so well known. 



Proc. Zool. Soc. -1884, No. VIII. 8 



