1909.] N. Annandai^E : The Indian Cirripedia Pedunculata. 97 
from the occludent. Scutum not much inflated, its vertical length about six times 
the length of the occludent margin of the tergum ; external surface bearing a single 
well-marked semicircular ridge, which extends from near the umbo on the occludent 
margin to the point where the carina, tergum and scutum meet; a strong umbonal 
tooth on both scuta. 
Peduncle relatively stout, ver}'- short. 
Cirri, etc. — First cirrus widely separated from second; its anterior ramus reaching 
the distal extremity of the penultimate joint of the posterior ramus; rami with 
eight or nine joints, slender with both margins spinose. Other cirri normal, with well- 
developed anterior fringes and posterior bunches of bristles; the number of bristles 
in each of the latter being variable. Anal appendages short, uniarticulate, truncated, 
bearing a row of short bristles at the tip. Penis moderately long, slender, bearing 
numerous fine scattered hairs on its surface and a somewhat less sparse bunch of 
similar hairs at the tip. 
Mouth parts somewhat variable, as in most species of Pœcilasma and Mega- 
lasma. Labrum bullate, with a row of small triangular teeth. Maxilla with the biting 
edge forming a ^-like outline, the excavation being deep and rounded and having its 
inner margin with a curved and gradual slope; three stout spines external to the 
excavation, several fine hairs at its base and about twelve slender spines on its inner 
margin and internal to it. Mandible with four or five teeth, the innermost tooth, when 
five are present, being narrow and spine-like; the greater part of the mandible covered 
with minute bristles arranged in small transverse rows of three or four bristles each. 
This species is common in the deeper parts of the Bay of Bengal and has recently 
been found in the Malay Archipelago. Pilsbry has described a very similar form 
from the S. Pacific under the name Pœcilasma bellum ' and later ® has published an 
elaborate comparison between this species and Megalasma minus. Undoubtedly 
differences exist between these two forms, and I find that most, though not all, of 
the differences noted by Pilsbry are constant. Moreover, I ow^e to his kindness the 
opportunity of examining a specimen of M. bellum. I do not think, however, that the 
two forms should be regarded as specifically distinct, for they seem to me to be 
merely local races, differing from one another in minute and comparatively unim- 
portant characters. The following table will serve to distinguish them from one 
another, but I should not be surprised to find that other “ species ” in the genus 
should (if my views as to what constitutes a subspecies be correct) be regarded as sub- 
species of M. minus. 
Megalasma minus. 
Race I (typical form). — Vertical length of scutum at least twice the greatest 
transverse diameter. 
Race II {Megalasma bellum, Pilsbry). — Vertical length of scutum less than twice 
the greatest transverse diameter. 
1 Bull. Bur. Fisheries, xxvi, p. 183, pi. iv, fig. 6 (Washington, 1907). 
* Proc. .Acad. Nat. Sei. Philadelphia , lix, p. 409 (1907). The first paper was written some time 
before publication. 
