ON INDO-MALAYAN BARNACLES. 77 



might be some grounds for regarding it as the representative of a new genus, but (leaving 

 out of account the fact that it is only known from a single specimen which was probably 

 living under abnormal conditions), its affinities lie so clearly with Scalpellum that I do not 

 think this course would be justifiable. In the type both mandibles have been examined ; 

 their condition seems normal, as there is no variation between the left and the right. 



Scalpellum sociabile, sp. no v. 

 Description — 



Capitulum sub-triangular, with occludent edge of valves straight and vertical ; 14 

 delicate, opaque, white, striated plates with lines of growth well marked on their ex- 

 ternal surface ; plates entirely covered and partially concealed by a thin, tough, hairy 

 membrane of a brownish shade, not very widely separated from one another, perfectly 

 calcified. The hairs are short and rather coarse, most aboundant over the carina, the oc- 

 cludent margin of the terga and scuta and the base of the capitulum. Carina simply 

 bowed in a moderate arc, its free extremity in contact with the terga but not between 

 them ; dorsal surface slightly concave, with borders feebly developed ; lateral margins 

 almost straight ; umbo terminal. Terga large, triangular, with scutal margin sloping up- 

 wards from carinal to scutal margin, which is straight and vertical ; carinal margin 

 straight, forming an acute angle with occludent margin ; umbo terminal, not retroverted. 

 Scuta irregularly quadrilateral, subtriangular ; occludent margin slightly convex outwards ; 

 basal margin practically straight, horizontal ; lateral margin almost straight, meeting 

 tergal margin, which is also almost straight, at an acute angle ; umbo terminal, overlap- 

 ping tergum slightly, feebly retroverted ; a portion of the plate, forming a scalene triangle 

 with the junction between the tergal and lateral margins as apex, depressed from with- 

 out, the remainder being convex outwards and concave from within. Median Latus an ir- 

 regular pentagon with the dorsal angle very acute, inclined towards the scutum ; basal 

 and carinal margins forming an obtuse angle. Carinal Latus horn-shaped, protuberant, 

 with the free extremity turned upwards and slightly inwards ; the bases of the two latera 

 meeting behind the carina. Inframedian Latus small, subtriangular, with apex uppermost 

 but reflected slightly above the upper margin of the carinal latus. Carinal latus long, 

 narrow, with its lower margin slightly excavated and its upper margin correspondingly 

 arched, blunt towards inframedian latus, sharply pointed over rostrum. Rostrum small, 

 triangular, generally overlapped at least partially by the carinal latera, concealed beneath 

 membrane. 



Pedtincle cylindrical, but often swollen irregularly in the middle ; generally more 

 or less contracted at the base ; of varying length, with eight or nine alternating series of 

 narrow, oval plates ; about eight plates in each series, all covered with hairy membrane. 



Dimensions- 



Length of Capitulum ... ... 31mm. 



Breadth of ,, ... ... 20 



Thickness of ,, ... ... 10 



?> 



