88 TIIE VOYAGE OF H.M.S. CHALLENGER. 



of the outer lip and also at the junction of the pillar-lip to the body; pearly within. 

 Outer lip very slightly descending at its insertion, then in its sweep rising a little : it is 

 scarcely angulated at the lower carina and at the point of the pillar, but it is a little 

 sinuated at that part ; it is thin on the edge, but is thickened within by a pretty strong 

 pearly callus and outside by a slight rounded marginal varix. Pillar-lip is hollowed back 

 into the pillar in a sinus, and is sharply reverted, so as to leave a minute but deep furrow 

 behind it ; this reversion ceases just before it reaches the umbilical thread, and forms a 

 minute tooth at that point. Umbilicus wide and pervious, but narrowed within ; its 

 slope is scored with minute sharp curved laminae, the remains of the old edges of the 

 pillar-lip sinus. H. 0-18 in. B. 0-27, least 0'17. Penultimate whorl. 0"04. Mouth, 

 height 0-1, breadth 0"1. 



In general aspect this is very like Trochus {Margarita) gemmulosa, A. Ad., but that species has 

 the spire lower, the suture distinctly depressed, the sutural furrow is beset with close radiating stria3, 

 the spiral threads are more numerous and crowded, the pointed tubercles on these are more frequent, 

 and there is no varix on the outer lip. This last is a feature which gives a great peculiarity to this 

 species ; but the thickening and the patulousness of the lip are not sufficient to connect it with Gaza. 

 The distinct umbilicus and the absence of a tooth narrowing the mouth separate it obviously from 

 Craspcdolus. 



53. Trochus {Margarita) azorcnsis Watson (PL V. fig. 12). 



Trochus^ (Margarita) ' azorensis, Watson, Prelim. Report, pt. 4, Joum. Linn. Soc. Lond., vol. xiv. 



p. 710. 



Station 75. July 2, 1873. Lat. 38° 38' N., long. 28° 28' 30" W. Fayal, Azores. 

 450 fathoms. Volcanic mud. 



Animal. — Dark in colour. Operculum rather strong, dark horn-colour, of very 

 many narrow whorls, which on the outside are flanged with a thin, narrow, overlying 

 border. 



Shell. — Small, strong, but not thick, conoidal, high, with rounded contours, slightly 

 angulated, scalar, sculptured, whitish, with a slightly flattened base and a small umbilicus. 

 Sculpture: Spirals — there are very many close, unequal, irregular small furrows, which 

 are feebler on the base and strongest near the suture, which is marginated below by a 

 narrow smooth line round the top of the whorls. In the centre of the base is an umbilical 

 depression with spiral threads in the bottom, and within this is a strong white porcellanous 

 spiral cord, wdiich almost closes the umbilicus. Longitudinals — the top of the whorls is 

 gathered into broad rounded oblique puckers, which die out before reaching the suture or 

 the base. Besides these, the whole surface, spiral furrows and all, is sharply scratched 



