510 verrucim:. 



Caudal Appendages. — These are of most unusual length, 

 sometimes even exceeding those of Ibla quadrivalvis, which 

 surpasses, in this respect, all other cirripedes. They 

 arise on each side and over the anus. They consist of 

 numerous (sometimes as many as twenty-four), unequal, 

 cylindrical, thin segments, bearing, at their upper ends, a 

 circle of long and very slender spines. They sometimes equal 

 two thirds or even four fifths of the length of the sixth cirrus ; 

 but their length, and the number of their segments, (some- 

 times imperfectly divided), varies much in different speci- 

 mens of the same species, and sometimes even on opposite 

 sides of the same individual. In some very young shells, 

 as big as a pin's head, the caudal appendages were pro- 

 portionally extremely short, and consisted of only two or 

 three segments. No muscles enter these organs ; and when 

 the animal is taken out of its sack, they project straight out 

 behind, instead of being curled in, like the cirri. 



Anatomical Structure. — The animal's body is attached to 

 the two scuta by the adductor scutorum, and by the other 

 usual muscles running towards the mouth, and surrounding 

 the prosoma. The whole external covering or shell has no 

 other muscles ; Verruca thus differing from the Balanidae and 

 Lepadidse ; but the shell is attached all round, near its cir- 

 cumference, to the basal membrane, by a band of very short 

 fibres, appearing like muscles, but really ligamentous, as 

 determined for me bv Professor Quekett. Branchiae are 

 entirely absent. The alimentary canal presents all the 

 usual characters, but in the prosoma is rather abruptly 

 bent back on itself. The orifices of the two olfactory 

 pouches are not at all prominent ; they are placed directly 

 under the outer maxillae, (homologically in their middle 

 segment), just above a small, medial, tongue-like apodeme. 

 The orifices of the acoustic sacks appeared to be in 

 their usual position beneath the basal articulations of 

 the first pair of cirri. The vesicular seminales occupy 

 their usual position in the prosoma ; they are not much 

 convoluted ; they unite before entering the penis. The 

 probosciformed penis is imperfectly ringed ; it is thick and 

 short, and tapers much more abruptly than is usual ; it 

 supports a few very thin hairs. The ovarian caca are 



