114 Memoirs of the Indian Museum. [Vol. II, 



The above description and notes were drawn up before I realized that I was deal- 

 ing with specimens both from the Atlantic and from the Indian Ocean, or that the 

 species had already been described ; for it was only on looking up the localities of the 

 crabs in the Museum register and referring to Pilsbry'spaper on the Cirripedes of the 

 U. S. National Museum that I discovered these facts. On doing so I re-examined the 

 specimens with the greatest care, to see whether I had overlooked any difference 

 between the two races, and also dissected two more specimens from each lot with the 

 same end in view. One character made it easy to distinguish the individuals found 

 on the American crab {Geryon quiquedens) from those on its Indian ally G. affinis, 

 namely, their colour; for the former were tinged with orange, the latter white. In 

 itself this is not an important matter, for if two lots of specimens of the common 

 oriental species Dichelaspis warwickii from different crabs from the same locality be 

 examined, they will often be found to differ in colour. The appendages, penis and 

 mouth parts of the two lots of specimens of D. geryonophila agree closely. I cannot, 

 therefore, separate the one from the other. 



The occurrence of any species of the genus on allied species of crabs so widely 

 separated in habitat is an extremely interesting fact, and, so far as I am aware, as yet 

 one without parallel. The American specimens in this Museum are from the same 

 locality as those on which the species was founded. Regarding it its author says, 

 "It is an abundant species, only known from the gill cavity of the crab Geryon 

 qinnquedens , and taken only in a rather small area off the continental slope east of 

 New Jersey, in 435 to 1,043 fathoms." So far as I am aware, only one specimen of 

 Geryon a-ffinis is known from Indian seas,' and I am pretty sure that this is the only 

 crab in our collection to which the barnacle is attached. 



Dichelaspis grayii, Darwin. 



D. grayii, Darwin, Mon. Cirr., Lep., p. 123, pi. ii, fig. 9 (1851). 



D. pellucida, Darwin, op. cit., p. 125, pi. ii, fig. 7; Hoek, Journ. Linn. Soc. 



London, xxi (Anderson's "Fauna of Mergui"), p. 154, pi. xiii (1889); 



Annandale in Herdman's Report on the Ceylon Pearl Fisheries (Roy. Soc, 



London), pt. v, p. 140, figs, i, Ta,ib (1906); Illustr. Zool. ''Investigator," 



Crust. Ent., pi. iv, figs. 2, 3 (1908). 

 All the tissues very transparent ^' ; no cuticular plates or spines on the surface. 

 Capitulum bonnet-shaped, compressed; the carinal margin irregularly curved, 

 the basal half being much more boldly arched than the upper half ; the occludent 

 margin sinuous. Five narrow, widely separated valves, which vary considerably as 



1 This crab was originally taken by the " Hirondelle" Expedition off the Azores and was described by 

 Milne Edwards and Bouvier in their account of the Decapod Crustacea of that expedition. Thanks to the 

 kindness of Prof. Bouvier and H. S. H. the Prince of Monaco, I have been able to examine barnacles 

 attached to Atlantic specimens. They were all specimens of Pœcilasma kœmpjeri subsp. auraniia. 



^ In life they have a pale vinous tint, which varies in intensity in individuals living in the same snake 

 and disappears very rapidly on spirit or formalin. 



