1885.] 'lightning' AND 'porcupine' EXPEDITIONS. 5.5 



Distribution. Off Sahara, C. Verd I., and Azores ('Talisman' 

 Exp.); 681-1261 fms. 



This elegant shell is closely allied to Cerithiella whiteavesii of 

 Yerrill, from the coast of New England, and may be the same 

 species. 



5. Cerithium obeliscoides^ Jeffreys. (Plate VI. figs. 4, 4 a.) 

 Shell pyramidal, rather thin, semitransparent, and glossy : 



sculpture, more or less numerous fine and rounded longitudinal striae, 

 which are crossed by a few spiral striae : of the latter there are 5 or 

 6 on the last whorl, 4 or 5 on the penultimate, and 3 or 4 on the 

 following three or four whorls ; the second whorl is marked by close- 

 set and more curved longitudinal striae ; the top whorl is quite smooth, 

 as well as the base of the shell ; the intersection of the two sets of 

 striae gives a reticulated but not a decidedly nodidous appearance ; a 

 considerable space below the suture in each wliorl has the longitudinal 

 striae only : colour milk-white : spire gradually tapering to a very 

 blunt point : whorls 7-9, convex; the last is equal to two fifths of 

 the spire in length ; the first whorl is bulbous, and in some specimens 

 is larger and broader than the succeeding whorl : suture rather deep, 

 defined by the lowest and thread-like of the spiral striae : mouth as 

 in the other species of this section, but smaller and with a shorter 

 groove : outer lip thin, scalloped : inner lip inconspicuous : pillar 

 fiexuous, L. 0-175, B. 0*05. Some imperfect specimens show that 

 this species attains a comparatively much greater size. 

 'Porcupine' Exp. 1870: Atl. St. 16, 17, 1 7a. 



6. Cerithium cylindratum^ Jeffreys. (Plate VI. figs. 5, 5ff.) 

 Shell rather cylindrical, thick, opaque, lustreless : sculpture, 



numerous straight "longitudinal striae, which are crossed by fewer 

 and finer spiral thread-like striae, so as to present a reticulated 

 appearance and to make the points of intersection tuberous or sca- 

 brous ; the spiral striae are 4 on the last whorl, besides a basal line 

 below the periphery, and 3 on each of the preceding whorls ; the 

 second, and sometimes also the third, whorl is marked with close-set 

 and curved longitudinal striae ; the first whorl is quite smooth and 

 glossy : colour pale yellowish-brown : spire gradually tapering to a 

 blunt point : whorls 10-12, rounded but compressed ; the last equals 

 about one third of the length of the shell ; the first is bulbous and 

 like that of the last species : suture narrow but distinct : mouth as 

 in all the foregoing species : outer lip thickish and prickly : inner 

 lip filmy: pillar fiexuous. L, 0^2, B. 0-075. 



'Porcupine' Exp. 1870: Atl. St. 27-30, 36; Med. Benzert 

 Road, Rasel Amoush, Adventure Bank. 



This has somewhat the aspect of Cerithiopsis tubercularis, but 

 the apex and mouth are those of a typical Cerithium. 



^ Like an obelisk. ^ Cylindrical. 



