EEPORT ON THE CIRRIPEDIA. 43 



number still) arc massed together into large floating balls ; smaller (younger) specin 

 axe, as a rule, observed among the larger ones. 



The shell of the Lepas is often inhabited by an Annelid, as well as by the Lepas itself. 



The bottles with the Lepas fasi-irn/n ris are labelled July 6, 1875, North Pacific, 

 surface (between Stations 248 and 240). 



Great collections of larvae in the first and in the later Nauplius-stages were made 

 about the same locality in the Pacific. 



Pcecilasma, Darwin, 1851. 



Darwin founded the genus Pcecilasma for those Lepadids with the carina extending 

 only to the basal points of the terga, with nearly oval scuta, having the umbones at the 

 rostral angle, with the lower end of the carina either truncated or produced into a deeply 

 embedded disc. 



Gerstaecker (in Bronn, loc. cit., p. 535), moreover, has stated in his description of this 

 genus, that the caudal appendages are uniarticulate and always furnished with bristles, 

 that the mandibles have four teeth, and that the anterior ramus of the second cirrus is 

 not thicker than the posterior ramus. 



Darwin describes five species of this genus. As far as my knowledge goes, no new 

 species has been discovered since the appearance of his monograph. 



Among the Lepadids of the Challenger I found two different forms which I believe 

 must be considered as species of this genus ; only it will be necessary to extend somewhat 

 the generic description as given by Darwin. This, I think, is more in accordance with 

 the principles followed by the author of the monograph of the Cirripedia, than 

 to resolve on the creation of a new genus for even- small deviation from the description 

 proposed. Darwin has shown, by placing Lepas fascicularis, Ellis, in the genus Lepas, 

 as well as by publishing the above copied diagnosis of the genus Pceci/csmti, that he 

 admits a considerable amount of variation in the shape of the carina within the limits of 

 a single genus. And it is just the shape of that same carina which alone renders it 

 difficult to place the two Challenger forms in the genus Pcecilasma. But as these forms 

 in all other regards agree entirely with the generic description, I think this difference < f 

 less importance. Both species have the carina neither truncated nor produced into a deepbj 

 embedded disc; its two sides are considerably enlarged downwards, making the carina 

 itself much deeper than in any of the other species of the genus (PL I. fig. 8 ; PI. II. fig. 2). 

 I therefore propose to include within the diagnosis of the genus Pcecilasma, Darwin 

 (Hoek), the following description of the carina : the lower end of the carina either 

 truncated or produced into a deeply embedded disc, or keel-shaped and considerably 

 enlarged. 



