BRACHYURA. 409 



Actumnus setifer (db Haan), var. setifer A. 3, p. 202. 



Localities : Pearl banks, Gulf of Manaar, one specimen (adult ? ) ; deep water off 

 Galle, one specimen (ovigerous ? ) ; Trincomalee, one specimen (ovigerous ? ). 



Description : In these specimens the areolas are more distinct than in the figures 

 of either de Haan or of A. Milne-Edwards. Moreover, the tomentum gives place 

 to a slight pubescence, and the general appearance is reminiscent of A. rienucosus, 

 Henderson, from which the specimens may, however, be distinguished as in Alcock's 

 key by having the lobule of the lateral gastric region semicircular instead of 

 w - shaped. 



Renuwks. The specimens suggest that an examination into the specific distinctness 

 of A. setifer, A. bonnieri, and A. verrucosus is desirable. 



Actumnus verrucosus, Henderson, 1893 A. 3, p. 203. 



Localities : Pearl banks, Gulf of Manaar, 25 specimens ; coral reefs, Gulf of 

 Manaar, five specimens ; Muttuvaratu Paar, one specimen. 



Remarks. There is in the British Museum a single adult male specimen of this 

 species labelled in Miers' (?) writing "Actumnus ceylonicus, Miers Ceylon. Presented 

 by E. W. H. Holdsworth, Esq. 1875." I am not aware that he published any 

 description of the crab. 



A. verrucosus is very closely allied to A. setifer on the one hand and to A. bonnieri, 

 Nobili, 1905, on the other. 



Actumnus bonnieri, Nobili, 1905 (N., p. 132, pi. vi., fig. 32). 



Localities : Pearl banks, Gulf of Manaar, two specimens (one adult ? ) ; deep 

 water oft' Galle, one specimen (ovigerous ? ). 



The present examples of A. bonnieri agree well with Nobili's description and 

 photograph. They are smaller than the average of verrucosus specimens known to 

 me. The difference between the two species in question is mainly a difference in the 

 form of the lateral gastric lobe. A similar distinction does not separate it from 

 A. setifer, though other differences hold here. 



Apart from the characteristic w -shaped lateral gastric lobe of A. verrucosus, the 

 characters which separate A. setifer var. tomentosus, A. setifer var. setifer, A. verru- 

 cosus, and A. bonnieri from each other are highly variable. An exact knowledge of 

 the variation within large samples is very desirable. Such variable characters are : 

 (l) C.b. -T-C.L, (2) convexity of carapace, (3) distinctness of areolae, (4) hairiness of 

 carapace, (5) condition of outer angles of front, (6) condition of fissure in lower 

 orbital margin (?), (7) granulation of wrist. 



Actumnus fissifrons, Alcock, 1898 A.3, p. 204; A.Invest., pi. xxxvii., fig. 5. 



Locality : Deep water off Galle, one specimen (adult 6 ). 



3 G 



