REPORT ON THE GASTEROPODA. 345 



distinct), 1 suggested by Dr Gwyn Jeffreys, I was enabled to obtain through the kindness of the 

 Marquis de Monterosato. Pleurotoma (Mangclia) corallina resembles that other in the minute blunt 

 prickles which are found on many corals, and which ornament the spirals ; but the Challenger species 

 is far smaller and narrower, the last whorl in particular is very much shorter and less tumid, the 

 whorls are always more angular, the spirals are fewer, the longitudinal ribs are both fewer and 

 stronger, and the apex is utterly different both in form and sculpture. 



75. Pleurotoma {Mangelia) rnacra? Watson (PI. XXIII. fig. 6). 



Pleurotoma {Mangelia) macra, "Watson, Prelim. Report, pt. 9, Journ. Linn. Soc. Lond., vol. xv. p. 437. 



Station 73. June 30, 1873. Lat. 38° 30' N., long. 31° 14' W. West of the Azores. 

 1000 fathoms. Pteropod ooze. Bottom temperature 39°'4. 



Station 78. July 10, 1873. Lat. 37° 26' N., long. 25° 13' W. Off San Miguel, 

 Azores. 1000 fathoms. Volcanic mud. 



Shell. — High, narrow, biconical, fragile, translucent white, glossy, feebly ribbed and 

 spiralled, with a stumpy subscalar spire, ending in a large, conical, sculptured, sharp-tipped 

 dome, and with a small body-whorl, contracted base, and produced snout. Sculpture: 

 Longitudinals — there are on the last whorl about 20 flexuous oblique threads ; they rise 

 at the suture, retreat very much in the sinus-area, but at the angulation below this 

 they curve forward and die out on the base ; the flat intervals which part them are 

 three times their breadth ; the system of longitudinal ribs on the embryonic whorls is 

 very much like that of the shell, but is really different : the lines of growth are 

 very fine, and are quite independent of the ribs. Spirals — below the sinus-area there is a 

 blunt angulation strengthened by a row of small tubercles on the ribs. The surface is 

 covered with very obsolete broadish threads, which are crowded on the body, but on the 

 base are stronger, more regular, and wider apart ; on the snout they are finer and more 

 crowded. The suture is marginated below by a flat thread. Colour almost papyraceous 

 white. Spire is subscalar, narrow, and would be high but for the abruptness with which 

 it is crowned by the apex, consisting of four yellow conically globose whorls, of which the 

 last is large and dome-shaped, and the first minute, prominent, but at the very tip slightly 

 bent down ; the first two are smooth ; the last two are sparsely crossed by minute cusp- 

 like threads or riblets. Whorls 7 to 8 in all, rather high, with a drooping shoulder in 

 the sinus-area, which is defined by the angulation below ; below this the upper whorls are 

 nearly cylindrical, while the body-whorl is barely convex : this whorl is small ; on the base 



1 The, minute ornamentation of the surface in these two species is very similar, and is apt to mislead ; but 

 the form of the whorls and the details, both of longitudinals and spirals, are different. The embryonic whorls, 

 too, are distinct, being in Pleurotoma {Rhaphitoma) nuperrima, Tib., broader and more pressed down ; the sculp- 

 ture is diverse also, the longitudinal ribs being the prominent feature in Pleurotoma nuperrima, Tib., while in 

 Pleurotoma hispidula, Jan., it is the spirals 



2 fiaxoo;, long. 



(ZOOL. CHALL. EXP. — PART XLII. — 1885.) Tt 44 



