322 OOLIECTIONS FKOM MELAHBSIA. 



have the articular ridges Bomewhat reflexed. For its distribution 

 see Darwin's monograph (p. 279), by -whom it is recorded from 

 Moreton Bay. 



3. Acasta sulcata, Lamarck, var. 



A single specimen in the collection from Albany Island, 3-4 fms., 

 is very doubtfully referred to this species. It agrees generally in 

 its external characters with Mr. Darwin's description, and also in 

 the broader spur of the tergiim of the operculum. In the remarkable 

 reduction of the width of the parietes of the carino-lateral compart- 

 ments it altogether resembles a specimen from Sydney iu Mr. 

 Cuming's collection (now in the British Museum) specially referred 

 to by Mr. Darwin* ; but it differs very remarkably in the external 

 armature of the parietes of the other compartments, which are 

 armed with strong, outwardly-projecting, hluntly-triangulate lobes 

 or teeth, one such tooth being situate on each compartment, not 

 very far below' the apex, except on the carina,^ where there are two 

 teeth ; thus there are five in all. The cup-shaped basis of the shell 

 is pinkish ; the epidermis, which remains upon the basal half of ^the 

 compartments, bright yellow. 



Mr. Darwin (t. c, p. 311) mentions some remarkable variations in 

 the external armature of this species, but none which at all resemble 

 the specimen now described. In the very closely allied A. spongites 

 the calcareous projections of the shell are often of considerable 

 size, yet not nearly so large as' the teeth in the specimen from 

 Albany Island, and much more numerous and irregularly distributed. 

 In the specimen of A. sulcata from Sydney, with narrow-linear 

 carino-lateral compartments, the walls of the shell are externally 

 smooth. 



* Monograph of Cirripedia, Eala>nidsB, p. 310 (1854). 



