148 Dr. II. Woodward — A New Cirripede from the Challx. 



Pedunculated Civripedes (LepadidjB), such as PolUcipes mitella 

 (PL VIII, Figs. 2a, 2b) and F. pobjmerns (Woodcut, Fig. 1), but 

 which are absent in ordinary sessile forms (Balanidee). 



Thus, in Dr. Eowe's specimen we have presented to us a Cirripede 

 of the greatest interest, offering a most important connecting link 

 between the more ancient Pedunculata or Lepadidje and the more 

 modern Opekculata or Balanid^. 



Turning to the genus Catophragmiis of Sowerby (Woodcut, Fig. 2), 

 we find a sessile Balanid which assists us in the interpretation of 

 Dr. Rowe's most interesting Chalk Cirripede, and also that Charles 

 Darwin had, in 1854, already pointed out the significance of the 

 structure of the shell in Catophragmiis as a means of bridging over 

 the interval between the sessile and pedunculated forms of Cirripedia 

 which Dr. Eowe's specimen had suggested to my mind Avhen he first 

 placed it in my hands at the end of last year. " This genus of 

 Catophragmiis," writes Darwin,^ " is very remarkable among sessile 

 Cirripedes, from the eight normal compartments of the shell being 

 surrounded by several whorls of supplemental compartments or 

 scales : these are arranged symmetrically, and decrease in size, but 

 increase in number towards the circumference and basal margin. 

 A well-preserved specimen has a very elegant appearance, like 

 certain compound flowers, which when half open are surrounded 

 by imbricated and graduated scales. The Chthamalin^, in the 

 structure of the mouth and cirri, and to a certain extent in that 

 of the shell, fill up the interval between the Balaninee and 

 Lepadida? ; and Catophragmus forms, in a very remarkable manner, 

 the transitional link, for it is impossible not to be struck with the 

 resemblance of its shell with the capitulum of Pollieipes (see 

 Fig. 1). In Pollieipes, at least in certain species, the scuta and 

 terga are articulated together; the carina, rostrum, and three pairs 

 of latera, making altogether eight inner valves, are considerably 

 larger than those in the outer whorls ; the arrangement of the latter, 

 their manner of growth, and union, all are as in Catophragmus. If 

 we in imagination unite some of the characters found in the 

 different species of Pollieipes, and then make the peduncle so 

 short (and it sometimes is very short in P. mitella) that the valves 

 of the capitulum should touch the surface of attachment, it would be 

 impossible to point out a single external character by which the two 

 genera in these two distinct families could be distinguished : but 

 the more important differences in the arrangement and nature of the 

 muscles, which are attached either to the opercular valves or surround 

 the inside of the peduncle, would yet remain." 



Although Dr. Eowe's Cretaceous Cirripede lacks the opercular 

 valves, it enables us to conclude, from the presence of the thi'ee or 

 four rows of imbricated scales around the base of the capitulum, that 

 this form must at once be removed from the genus Pyrgoma, with 

 which, as one of the Balanina?, it has onl}' a very remote affinity. 



1 A Monograph of the Subclass Ch-ripedia : The Balauida', etc., pp. 48-5-7, 

 pi. XX, fig. 4. Ray Society, 1854. 



