450 Records of the Indian Museum. [VoE.cxas 
There must, I think, be some mistake about a specimen in the 
Indian Museum collection that is supposed to have been collected 
by Major Beddome in South India. 
This is the largest form of P. ceylonicus known, and full-grown 
specimens may easily be distinguished from the varieties gracili- 
brachiatus and pusillus by their size. Younger specimens may be 
distinguished by the loss, at a time when the size of the specimen 
is greater than that at which these changes take place in the per- 
manently smaller forms, first of the bright and chequered juvenile 
colouration, and later of the first of the three spines on the upper 
surface of the distal end of the tibia of the arm. But in the 
smallest specimens of all there appears to be no certain means of 
distinguishing the different forms. 
The fully grown female of var. gracilibrachiatus is the only 
other form at all likely to be confused with this typical form. 
It approaches the typical form much more closely in size than do 
either the male of the same variety or either sex of var. puszllus ; 
and, except when their maturity is made evident by the presence of 
embryos under the abdomen, the identity of these forms is very 
difficult to establish unless by comparison with a good series of 
typical specimens in various stages of growth. 
The presence of a pair of well-developed semilunar lobes on 
the posterior margin of the third abdominal sternum of P. ceylonicus , 
s. sty., is useful in checking the identity of immature specimens, as 
in the varietal forms these are always proportionally smaller than 
is usual in the typical one, and they are often apparently absent 
altogether. But as, in a long series, every stage can be found 
from their absence in the varieties to their full development in the 
typical form, their condition does not in itself fully indicate to 
which of the three forms a specimen belongs. 
The following measurements of the mature or approximately 
mature specimens in the Indian Museum collection will serve to 
indicate the proportions borne by the arms to the width of the 
carapace in adults of this form :— 
2 (with | 
Sex. 3 em- cl Jb ref ref 
bryos). 
Width of carapace in mm. 18 17°5 17 160 16 15 
Length of femur of arm in kat es : - 
iit 40°5 520 34 33 33 31 
2. P. CEYLONICUS var. GRACILIBRACHIATUS, Gravely. 
The habits of this form resemble, so far as is known, those of 
the next variety. 
The Indian Museum collection contains specimens from the 
following places in Ceylon :— 
