528 THE VOYAGE OF H.M.S. CHALLENGER 



This species seems to be somewhat variable in size, one of the five specimens which represent it- 

 being a good deal larger than the rest, with the same number of whorls. Another specimen is more 

 dumpily conical. 



It has some resemblance in a general way to Cerithwpsis metaxa, (Chiaje), but in that the 

 contour lines are more regularly conical, the spire is not at all scalar, the whorls are convexly 

 rounded, there is no deep sutural furrow, the tuberculations are long across the shell, and each whorl 

 has four, not three spirals ; the form of the base is a good deal like, but the pillar is shorter, 

 stronger, straighter, rounder, and has not the sharp-flanged edge of that species. From Cerithiopsis 

 tubercularis, Mont., which it resembles in sculpture, it differs not only in its slender form, but in the 

 absence of the circumcolumnar thread on the base. 



The species it most resembles is Cerithiopsis barleei, Jeffr., from which it differs in having a 

 slightly shorter apex, scored with stronger, less superficial, fewer, and less oblique longitudinal riblets. 

 The first 1J regular whorls have only two spiral threads, and the ribs there are stronger than in 

 Cerithiopsis barleei. The suture throughout is less strong and open, the circumbasal thread is 

 stronger and more nearly tubercled, and the base within this thread is slightly depressed ; the scar 

 of the old canal is barely traceable. 



Dr Gwyn Jeffreys (Moll. " Lightning " and " Porcupine," Proc. Zool. Soc. Lond., 1885, p. 60) 

 was mistaken in identifying this species with Cerithiopsis diadema, Wats. The points of distinction 

 are sufficiently indicated in my paper on N.E. Atlantic Cerithiopsides (loc. cit., pp. 92, 93). He was 

 also mistaken in thinking that the Marquis of Monterosato had confused them. 



4. Cerithiopsis ridicula, 1 n. sp. (PI. XXXVIII. fig. 1). 



Station 186. September 8, 1874. Lat. 10° 30' S., long. 142° 18' E. Off Wednesday 

 Island, Cape York, North-east Australia. 8 fathoms. Coral mud. 



Shell. — Very small, oval, dark-brown, with three rows of strong tubercles on each of 

 the three later whorls, a deeply furrowed suture, a contracted last whorl, and a high 

 white apical spike. Scutyture: Longitudinals — there are rows of raised and rounded 

 threads, parted by rather deep square furrows of nearly the same size as the threads ; 

 these rows run continuously down the spire, being only interrupted by their splitting into 

 two here and there as the rows increase in number (to about 20 on the last whorl). 

 Spirals — there are on each of the three regular whorls three threads much like the longi- 

 tudinals, and parted by similar furrows ; these threads, in crossing the longitudinals, are 

 topped by small neat round tubercles, which quite cover the intersection ; on the back of the 

 outer lip they are elongated ; the highest row of these tubercles is slightly the largest of 

 the three ; on the full and produced base there is one spiral thread which is subtubercled, 

 a second, strong but without tubercles, coils round the bottom of the pillar, and the third 

 half-way up the pillar is small, but still rather strong. Colour dark transparent brown, 



1 So called from the pretentiousness of its extreme smallness. 



