REPORT ON THE GASTEROPODA. 87 



It may be observed that I have put a mark of interrogation to the station whence this species 

 comes. The solitary specimen had been sent to Mr Henderson that he might deal with the Pajurus 

 it contained. Mi' Henderson, in handing it to me, expressed some doubt of the accuracy of the 

 station-marking, as the Pajurus living in the shell was a North Atlantic species. The Trochus 

 itself also suggests to me that locality rather than the shallow water of a South Pacific locality like 

 Station 304. 1 



52. Trochus (Margarita) pachychiles, 2 Watson (PL V. fig. 11). 



Trochus (Margarita) pachychiles, Watson, Prelim. Report, pt. 4, Joura Linn. Soc. Lond., vol. xiv. 



p. 708. 



Station 201. October 26, 1874. Lat. 7° 3' K, long. 121° 48' E. Philippines. 82 

 fathoms. Stones and gravel. 



Shell. — Small, conical, with the last whorl tumid, especially toward the mouth, which 

 is extremely oblique, and has a thickened lip; carinate, widely umhilicate. Sculpture: 

 Spirals — in the centre of the body-whorl is a strong carinal thread, which almost runs into 

 the outer lip at its junction with the body, but just lies above it, and so stands out round 

 the base of the whole earlier whorls ; this thread is set with strong, sharp, remote tubercles, 

 which become feebler and more crowded toward the mouth ; half-way between the carina 

 and the suture is another thread, set with feebler tubercles ; these two threads only aj>pear 

 on the second regular whorl, but on the body-whorl, especially towards the mouth, many 

 others make their appearance; a little below the carina, and issuing from the junction of 

 the outer lip is a feebler tubercled thread, defining the base. On the base are three strong 

 closely-beaded threads, the inmost of which defines the umbilicus, within which is a finer 

 beaded thread, and, deep inside, a ridge. Longitudinals — all the upper whorls are crossed 

 by strong straight ribs, forming tubercles where they cross the spirals, and leaving deep 

 square hollows between. Only on the penultimate whorl do these become oblique and 

 feebler, till toward the mouth they are narrow, weak, crowded, and broken. Besides 

 these, the whole surface is roughened with small, coarse, irregular lines of growth. Colour 

 dead white. Spire high and conical, but the tumidity of the last whorl, especially towards 

 the mouth, greatly detracts from this ; it is slightly scalar. Apex small. Whorls 6, of 

 slow increase till the last, angular, projecting out squarely from the suture, flattened on 

 the contour, and contracted below the carina; but the last whorl is rounded, tumid, and, 

 toward the mouth, expanded. The base is rounded, but not inflated. Suture very deep 

 and strong, from the overhanging of the carina above it. Mouth extremely oblique, 

 perfectly round but for a slight flatness across the body and an angulation at the insertion 



1 The Station nuraher is in all probability quite correct. — J. M. " •xayvyjiXn;, thick-lipped. 



