1909.] 
N. Annandale : The Indian Cirripedia Pedunculata. 
87 
is narrower than the carinal ; umbo at the rostral angle. Tergum triangular 
or nearly so, absent in one species. Carina forked at the base or expanded 
into a more or less well-developed transverse disk, not expanded vertically ; 
its apex reaching or extending for a short distance between the terga above ; 
its umbo basal. Peduncle well developed, naked, or bearing small chiti- 
nous plates. Filamentous appendages absent; caudal appendages consist- 
ing of a single joint, cylindrical or laterally compressed, not claw-shaped, 
bearing at the tip a pencil of fine hairs. Mandibles with four or five (rarely 
six) teeth, inclined to be variable; maxillae with the free edge straight or 
broken by a single incisure, not step-formed. 
This genus is easily distinguished from Lepas by the structure of its anal append- 
ages and maxillae ; it fades almost imperceptibly into Dichelaspis, from which it is 
only distinguished by the perfect development of its valves. From Megalasma, Hoek, 
* it is distinguished by the shape of the carina at the base — a character which is perhaps 
of no more than subgeneric value. 
Strictly speaking, as Darwin was well aware and as Pilsbry has recently pointed 
out, the name of the genus should be Trilasmis^ for a species was described under that 
name by Hinds in 1844. The species {T. eburnea), however, was an aberrant one, 
and the name has so long been obsolete that to revive it would only cause confu- 
sion. I have therefore neglected to follow the strict laws of priority in this 
instance, retaining Hinds’s name merely as that of a subgenus. 
Four * Indian species of Pœcilasma are known ; they may be distinguished as 
follows : — 
Key to the Indian species of Pœcilasma. 
I. 
II. 
III. 
IV. 
Valves complete ; scutal margin of tergum straight. 
A. Carina narrow, truncated at the base 
Scutum divided vertically ; scutal margin of tergum straight. 
A. Tergum with the occludent and apical angles more or 
less rounded and the carinal angle truncate . . 
Scutum divided vertically ; tergum present, its scutal margin 
excavated to correspond with the tip of the occludent margin 
of the scutum. 
A. Valves closely approximate ; occludent margin of the 
scutum strongly curved 
Tergum absent ; scutum inflated. 
A. Scutum with a strong internal tooth, not divided, but 
possessing a distinct vertical suture 
P. kcempferi. 
P. fissiim. 
P. miniitmn. 
P. ehurneum. 
^ The specimens identified as representing P. Hoek {Rec. Ind. Mus.,vo\. i, p. 81 (1907), 
are young examples of Megalasma minus, which, at an early stage, closely resembles P. gracile exter- 
nally. 
