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Show 1884.] 'LIGHTNING'AND ' PORCUPINE' EXPEDITIONS. 113 differs from R. scrobiculata of Moller in being cancellated and the peculiar sculpture of the apex. 6. RISSOA DICTYOPHORA, Philippi. R. 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 FISCHERI1, Jeffreys. (Plate IX. fig. 1.) S H E L L 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 equally 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. R. 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 Granata); but the sculpture is different. In the latter species it is finer, 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 R. tenuicostata, as well as in having a shorter spire and a proportionally larger body-whorl. It is also allied to R. 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. R. clathrata is a larger i Named in honour of Dr. Paul Fischer, whose conchological labours and especially his excellent 'Manuel de Oonchyliologie' are so well known. PROC. ZOOL. SOC. -1884, No. VIII. 8 |