REPORT ON THE CIRRIPEDIA. 47 



resemble almost exactly those of the foregoing species; beneath the notch there ifl 

 one slender spine, while numerous stronger spines are inserted in a double row on the 

 inferior upraised part. 



Cirri, — Posterior pair with segments bearing as a rule four pairs of spines, the lowest 

 pair of which is very minute, the second pair minute. Dorsally at the limit of two 

 segments, one stronger and two or three smaller spines are inserted. First pair of cirri 

 standing far separated from the second; rami about equal in length and thickness, less 

 than half as long as those of the second cirri. Second cirrus with anterior ramus not 

 thicker and only a trifle shorter than the exterior ramus ; the interior has fourteen, the 

 exterior fifteen segments. Both rami of third cirrus have a longitudinal row of slender 

 spines reaching to about the eighth segment. 



Caudal appendages about one-fourth of the length of the pedicel of the last cirrus, 

 with a row of slender spines at the extremity. 



Penis not very hairy. 



Size. — Entire length 8 mm., the capitulum measuring nearly 7 mm. 



During the Challenger Expedition one specimen was collected at Station 164a (off 

 Sydney, Australia); kit. 34° 13' S., long. 151° 38' E; depth, 410 fathoms; bottom, 

 grey ooze. 



Dichelaspis, Darwin, 1851. 



Darwin gives the following diagnosis of this genus : — Valves five, generally appear- 

 ing like seven, from each scutum being divided into two distinct segments, united at 

 the rostral angle ; carina generally extending up between the terga, terminating down- 

 wards in an embedded disc, or fork, or cup. Mandibles with three or four teeth ; 

 maxillae notched, with the lower part of the edge generally not prominent ; anterior 

 ramus of the second cirrus not thicker than the posterior ramus, nor very thickly clothed 

 with spines ; caudal appendages uniarticulate, spinose. 



As far as the animal's body is concerned, there is no important difference between this 

 genus and Poscilasma. It has been separated by Darwin from the latter genus, " being 

 so easily distinguished externally, that I have thought it a pity to sacrifice it." The 

 characteristic form of the scutum and the carina, which runs up between the terga, 

 make it easy, no doubt, to distinguish this genus from the other Lepadid-genera, to 

 which in other regards it shows great- affinity. 



Darwfin describes five species of this genus. Three species more have since been 

 described. In the first place, Diehelasj/is ilaririnii, de Filippi, from the Mediterranean, 

 then. Dichelaspis neptuni, Macdonald, sp., from Moreton Bay, Australia. This second 

 species has been introduced into science under the name Paniiln/cpas neptuni. However 

 there can be no doubt, I believe, but that it belongs also to the present genus. I even 



