1909.] N. Annandale : The Indian Cirripedia Pedimculata. 95 



the joints long and well developed. Anal appendages uniarticulate, cylindrical, rather 

 stout, rounded at the tip, which bears a bunch of bristles shorter than the appendage. 

 Penis short, pointed, slender. 



Mouth parts. — Labrum with very small chitinous teeth, which become almost 

 granular in the middle of the row. Outer maxilla very broad, truncated, subquad- 

 rangular, bearing numerous rather short and slender hairs on its inner surface. Max- 

 illa excavated, bearing three stout spines external to the notch ; the edge internal 

 to the main notch somewhat irregularly sinuated or serrated, sometimes with a second 

 notch not very much more shallow than the outer one ; the spines on the internal 

 part of the edge very stout ; the greater part of the maxilla covered with fine, short 

 hairs. Mandible bearing five teeth, the internal angle being dichotomous ; the inner- 

 most tooth more or less spine-like ; the notches between the teeth with their edges 

 more or less irregular, but not definitely serrated or pectinate ; the greater part of 

 the mandible covered with fine, scattered hairs. 



The largest specimen of the species that I have seen has a capitulum 6 mm. in 

 vertical length and 4-5 mm. in greatest transverse diameter. 



Pœcilasma eburneum is evidently a shallow- water species, although not exactly 

 littoral. It has only once been taken by the '' Investigator," so far as I can discover, 

 but on that occasion in considerable numbers. I have not, however, been able to 

 examine many of the Indian Echinoidea to which barnacles might be expected to be 

 attached, the greater part of the '' Investigator " collection being in the hands of a 

 specialist abroad. 



Genus Megalasma, Hoek (1883). 



Distinguished from Pœcilasma by its extremely broad carina, which is expanded 

 laterally but does not form a transverse disk at the base. Valves heavy 

 and fully calcified, the scutum entire. Peduncle invariably short. 



This genus was created by Hoek in 1883 for the reception of a single species 

 (M. striatum) and has recently (1907) been much extended by Pilsbry, who has not 

 only described several new species but has also included several others previously 

 ascribed to Pœcilasma. The latter species constitute in his opinion a subgenus of 

 Megalasma which he has called Glyptelasma ; they agree with the species of Megalasma 

 in the lateral expansion of their carinse but differ in the position of the umbo of 

 the scutum, which in the more typical forms of the genus has rotated through an 

 angle of 90° and taken up a position in line with the occludent margin, while in the 

 species included in Pilsbry's subgenus, as well as those left in Pœcilasma , the umbo 

 is situated at some distance from the margin of the capitulum. 



It is certainly very difficult to separate the species of Glyptelasma from those 

 of the typical Megalasma. Young individuals of M. mimes, which is as typical a 

 form as any, sometimes approach very closely to the subgenus, resembling M egalasma 

 {Glyptelasma) gracile in outlines with sufficient exactitude to deceive me as to their 

 correct diagnosis. No true species of Glyptelasma , however, has been reported from 

 Indian seas. 



