103 



Borradaile divides Upogebia into two subgenera, Gebiopsis 

 and Upogebia, distinguished as follows : — 



The thumb of the chelipeds almost or quite 

 as long as tlie movable finger ; no small tooth 

 on anterior edge of carapace above the 

 antenna, . . . . Gebiopsis, A. Milne-Edwards. 



The thumb of the chelipeds distinctly 

 shorter than the movable finger ; a small 

 sharp tooth on anterior edge of carapace 

 above the antenna, . . . . Upogebia, Leach. 



There are two British species, U. deltaura and U. stellata, but 

 the latter has not so far been recorded from Ireland. 



Upogebia (Gebiopsis) deltaura, Leach. 



Gebia deltura, Bell, 1853. 

 Upogebia deltaura, Borradaile, 1903. 

 Gebia deltura, de Morgan, 1910. 

 Gebiopsis deltura, Stephensen, 1910. 



It has been doubted by several writers whether U . deltaura 

 and U . stellata are really separate species. This is probably 

 due partly to the difficulty of obtaining specimens for comparison, 

 owing to the fossorial habits of the animals. Bell, though he 

 gives separate descriptions, is doubtful on the subject, and 

 is inclined to regard the differences between them as sexual, 

 and Norman (1906) looks on the two as synonymous. Borradaile 

 (1903), however, places them in different subgenera, separated 

 by the characters given above. The presence of the small tooth 

 above the antenna in U . deltaura and its absence in U . stellata 

 has also been noticed by de Morgan (1910) who has examined 

 numerous specimens, including o^^igerous females of both 

 species, so that there can no longer be any doubt of the differences 

 between them being specific and not merely sexual. 



The two species, then, may be distinguished by the following 

 characters. 



The abdominal plates are much broader in deltaura than in 

 stellata and the rostrum is less acute. Stellata is a much smaller 

 animal and when alive is covered with orange-coloured spots. 

 With regard to the chelipeds, the dactyl is very much larger 

 than the fixed finger in stellata, so that the appendage might 

 almost be called subchelate ; in deltaura, on the other hand, 

 the two fingers are nearly equal and the dactyl is thicker. 

 The rostrumx and gastric area of the carapace are thickly covered 

 with setae in deltaura ; they are much shorter and not so dense 

 in stellata. 



Size. — Full-grown individuals are often about 100 mm. long. 



General Distribution. — It is difficult to make out the 

 exact distribution of the species, as it is impossible to say hov? 



