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On the Species Upogebia stellata and Gebia deltura. 



By 

 W. De Morgan, F.Z.S. 



As remarked by Stebbing (A History of Recent Crustacea, p. 185) : 

 " Upogebia, Leach, 1814, was founded to receive another species dis- 

 covered by the industrious Montagu, and described by him in 1805 

 (1808) as Cancer astacus stcllatns. ... It seems to have escaped the 

 notice of writers subsequent to Leach that the earliest name of this 

 genus was Upogebia, which therefore must be retained in preference to 

 Leach's own alteration of it into Gebia, or Eisso's Gebios." 



Some doubt still appears to exist whether Upoejehia stellata (Leach) 

 and Gehia deltura (Leach) are distinct, or merely sexual forms of the 

 same species. 



Leach gives excellent figures of Gehia stellata (Malac. Fodoljjh. Brit., 

 table xxi, figs. 1-9) and Gehia deltura (figs. 9-10). He regarded them as 

 distinct species, and remarks of Gehia deltura : " This species lives with 

 Gehia stellata, with which it was confounded, until the distinctions 

 were discovered by Mr. J. D. C. Sowerby." I am unable to find out 

 whether Mr. Sowerby recorded his description. 



Bell (British Stedk-eyed Crustacea, pp. 223-5) describes Gehia stellata 

 and Gebia deltura under the gwius Gebia (Leach), of the Thalassinidae, 

 and gives good figures of both. He appears to doubt, however, whether 

 they are distinct species, and of G. deltura writes: "This species, if 

 it be indeed distinct, dilfers from the former, G. stellata, in the follow- 

 ing particulars : the whole animal is very much larger, sometimes not 

 less than twice the length, and more than proportionately wider. 

 The carapace is much broader and more spreading at the sides. The 

 legs are more robust ; the arm of the first pair is not more than twice 

 as long as it is broad, the wrist even shorter than broad, the hand 

 thicker, and tlie fingers more nearly of equal length. The sette of the 

 external antennre are shorter in proportion, being, according to Leach's 

 figure, not more than half the length of the body. The abdomen is 

 broader, more spread, and much less firm in its texture, the sides being 

 almost membranaceous, and the abdominal false feet larger and more 

 voluminous than in the other species. The different lamellfe of the 



