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 lohiteavesii of 

 Verrill, 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, semitrausparent, 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 strise ; the top whorl is quite smooth, 

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

 strise gives a reticulated but not a decidedly nodulous appearance ; a 

 considerable space below the suture in each whorl has the longitudinal 

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

 blunt point : whorls 7—9, convex ; t!ie 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 

 flexuous. L. 0"175, B. O'Oo. Some imperfect specimens show that 

 this species attains a comparatively much greater size. 



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



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



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 m.arked 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 flexuous. L, 02, B. 0"075. 



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

 Road, Basel Amoush, Adventure Bank. 



This has somewhat the aspect of Cerithiopsis tulercularis, but 

 the apex and mouth are those of a typical Cerithium. 



' Like an obelisk. ^ Cylindrical. 



