144 THE VOYACE OF II. M.S. CHALLENGER. 



narrow and hardly visible. The line where the two parts meet in other species is slightly 

 concave; in this species, however, it is either straight or even slightly convex. The 

 apex of (he carina, moreover, is at a much greater distance from the base in comparison 

 with the apc\ of the rostrum than is the case in the other species. In most specimens 

 the rostrum and the carina articulate together, as in Verruca nitida, by means of a 

 single tooth. The form of the shell, however, comes much nearer to that of Verruca 

 quad/rangularis. 



The fixed scutum and tergum are both elongate. The fixed scutum is triangular, 

 relatively large, and very convex, especially close to the basis. The fixed tergum has a 

 very narrow basal margin, but grows considerably broader towards the middle of the 

 valve. Its apex is like that of the scutum bluntly pointed. 



Two of the specimens are attached to small pieces of shell, the two others to small 

 horny tubes, wide at one extremity, and narrow, pointed, and closed at the other. I 

 think these are tubes once inhabited by small Aunebds. 



This species was taken in the North Atlantic at Station VI., January 30, 1873 ; 

 hit, 36° 23' N., long. 11° 18' W. ; depth, 1525 fathoms; bottom temperature, 

 1 0, 6 C. ; bottom, Globigerina ooze. 



Observations. — Together with the four specimens, for which I propose the uame Verruca 

 obliqua. another representative of the same genus was dredged. In most respects this 

 specimen is different, but especially in the form and relative size of the scutum ; it is 

 not only much larger, but it has, moreover, a distinct, freely projecting apex. The 

 tergum much resembles the same valve in most other species of this genus ; it is, however, 

 incomplete in the present specimen, its apex being broken off. Rostrum and carina form 

 together a shell, which is broader than that of Verruca obliqua, and at the same time 

 is not so high. In this respect it resembles Verruca nitida. The immovable tergum and 

 scutum are intermediate between those of Verruca nitida and of Verruca obliqua. I 

 figure the specimen in PL XII. fig. 17. I indicate it as Verruca obliqua, var. ; I should 

 find it, however, rather difficult to say why it is considered as a variety of this species, 

 and not, e.y., of Verruca nitida. 



Balanus, Auctorum. 



" It is not easy," Darwin says (loc. cit., p. 185), " to exaggerate the difficulty of identify- 

 ing the species, except by a deliberate examination of the internal and external structure 

 of each individual specimen." If Darwin came to this conclusion, after a study of years, 

 making use of the very rich collections of the British and other museums, and of private 

 collections (in the first place his own, chiefly made during the voyage of the " Beagle "), I 

 need hardly tell how great are the difficulties which I have had to surmount in identifying 



