1885.] MR. MIERS ON A THELPHUSA FROM KILTMA-NJARO. 237 



6. Description of a new Variety of River-Crab, of the genus 

 Thelphusa, from Kilima-njaro. By E. J. Miers, F.L.S., 

 F.Z.S. 



[Eeceived Febraary 3, 1885.] 



The species of Thelphusa, or River-Crabs, are extremely numerous, 

 and their discrimination is often very difficult, on account of the 

 changes which the species undergo as they increase in age and size. 



In the collection brought by Mr. H. H. Johnston from Kilima- 

 njaro are two specimens of this genus, which I assign, though not 

 without some hesitation, to the Thelphusa depressa, Krauss, de- 

 scribed from types taken near Pietermaritzburg, Natal. They agree 

 with the description and figure in tlieir depressed carapace, which 

 is considerably dilated at the branchial regions, in the non-develop- 

 meut of the lateral epibranchial tooth, and in other essential 

 characters ; but differ in the more strongly defined cervical suture of 

 the carapace, and the more strongly denticulated merus, and much 

 less strongly arcuated dactylus of the chelipedes. As regards this 

 latter character, I may observe that in a series of Thelphusce 

 (perhaps T. difformis^ in the Museum collection, the dactyli of the 

 chelipes are in some males arcuated, and in others nearly straight. 



I append a detailed description of the specimens from Kihma- 

 njaro, which I propose to designate T. depressa, Krauss, var. 

 johnstoni, but which may prove to belong to a distinct species. 



Thelphusa depressa, Krauss, var. johnstoni. 



C(. Thelphusa depressa, Krauss, Siidafrik. Crustaceen, p. 38, pi. 11, 

 fig. 4 (1843). 



Carapace transverse, widest in its post-frontal region, depressed, 

 with the dorsal surface nearly smooth, and divided into two nearly 

 equal portions by the zigzag cervical suture, which extends trans- 

 versely across the carapace to the postero-lateral margins ; behind 

 this a second transverse depression (not a suture) crosses the cara- 

 pace behind the cardiac region. The postfrontal crest extends to 

 the antero-lateral margins of the carapace, and is interrupted only 

 by the meso-gastric suture, which bifurcates posteriorly (as usual 

 in the genus) ; this crest is granulated near to the antero-lateral 

 margins, which are defined by a distinctly granulated line ; the 

 lateral epibranchial teeth are not developed. On the hepatic and 

 branchial regions are several faintly indicated lines, which extend 

 inward for a short distance over the dorsal surface of the carapace 

 from the lateral margins. The front is about one third the width of 

 the carapace, punctulated above, with its anterior margin sinuated, 

 its antero-lateral angles obtuse and not prominent. The orbital 

 margins are entire, and defined by a raised line, which is granulated 

 except near to the front ; the inferior orbital margin is regularly 

 arcuate, not (as in T. perlata) angulated near to the interior sub- 

 ocular lobe, which is not at all prominent ; the tooth, also, at the 

 exterior orbital angle is very little developed ; the parts of the 



