IQ09 - 1 N. Annandale : The Indian Cirripedia Pedunculata. 109 
D. tridens is apparently not uncommon in the seas of Sumatra and the Malay 
Peninsula, but it is not very often met with in Indian seas. It appears to prefer as 
hosts Crustacea such as Thenus orientalis which habitually live in rather shallow 
water but are also found at a depth of between 100 and 200 fathoms. As a rule it 
clusters on the mouth parts of its host and round the entrance to the gill-chambers 
or the base of the chelae. Occasionally, however, it also adheres to the gills them- 
selves and the membrane that covers them above. 
Like most species of its habits, D. tridens is small. In large adults containing 
eggs the capitulum measures about 3 ' 5 ^ 2\5 mm., and the peduncle is usually 
shorter than the capitulum. As a rule young individuals have the capitulum rela- 
tively narrower and the peduncle longer and more slender. I have found eggs, 
however, in the shells of individuals which had these characters. The peduncle varies 
considerably in length even in the larger specimens, and is smooth in some, annulated 
in others; the development of the chitinous points with which it is beset is also a 
variable character ; for in some large individuals they are minute, colourless and 
almost invisible, while in others they are much larger and have a deep yellow colour. 
Dichelaspis hathynomi , Annandale. 
D. bathynomi, Annandale, Ann. Mag. Nat. Hist. (7), vol. xviii, p. 45 (1906); 
Illustr. Zool. ' 'Investigator Crust. Ent., pi. v, fig. i. 
Capitulum regularly and somewhat narrowly ovoid, pointed above, rounded at 
the base, compressed, covered by the valves to a variable extent; the outlines of the 
five primitive valves and their lines of growth always distinct ; the calcified valves 
more or less hyaline, with an opaque area at the umbo. Dorsum large, subtriangular ; 
its umbo situated close to the carinal margin of the capitulum, its superior margin 
more or less curved and forming a contiûuous line with the carinal margin; rostral 
and carinal angles acute ; the scutal margin almost straight or excavated to corres- 
pond with the tip of the occludent segment of the scutum. Scutum in two segments, 
which diverge above to a variable extent ; the occludent segment rounded or truncate 
at the apex (at which point it is in contact with the dorsum), pointed at the base, 
regularly arched ; carinal segment variable in outline and extent, subtriangular or 
triangular, not reaching so high above as the occludent segment. Carina rather 
short, of variable lateral width, with more or less defined lateral ridges, expanding at 
the base into a transverse disk, which is much smaller than that of the carina of D. 
tridens. 
Peduncle fairly slender, cylindrical, of variable length, covered with small, 
chitinous tubercles which vary in size and colour. 
Cirri, etc. — First pair of cirri somewhat widely separated from second, re- 
sembling those of D. tridens, to which the species is closely related as regards its 
anatomy generally. Anal appendages uniarticulate, rather slender, bluntly pointed, 
bearing a short fringe of long bristles on the posterior margin of the extremity only. 
Penis of variable length, slender, pointed, covered with closely set rings of minute 
