442 DE. J. G. DE MAN ON CEUSTACEA CHIEFLY 



PoTAMON (Parathelphijsa) endtmion, de Man. (PI. 33. figs. 59-63.) 

 Potamon [Parathelphusa) endymion, de Man, in Zoologischer Anzeiger, xxx. 1906, p. 35. 



Two egg-laden females from the lake at Yunnan-Pu, China, that were collected 

 together with specimens of Potamon {Tarapotamon) spiuescens (Caiman). 



This species is related to Pot. spinescens, Caiman, and Pot. [Parapthelphusa) lanzi, 

 Doflein, but is of smaller size. 



Carapace three-fourths as long as broad, just as in Pot. spinescens, when the lateral 

 spines are included ; the carapace presents its greatest width at about one-third of its 

 length from the frontal margin. The upper surface, flattened on its posterior half, 

 curves anteriorly towards the rather steeply deflexed front ; it is also flattened trans- 

 versely, but the anterior branchial regions are somewhat swollen, more than in Potamon 

 spinescens, and they slope steeply down to the antero-lateral border, which is not the 

 case in Caiman's species. The two lateral furrows of the H-like figure on the middle of 

 the carapace are shallow, though distinct, but the transverse median part is hardly 

 discernible. On the outer side of each lateral furrow a transverse iaipression is 

 observed, bounding the inner part of the anterior branchial region posteriorly. The 

 posterior branchial regions are also somewhat inflated and separated by shallow 

 impressions from the anterior. The branchio-cardiac impressions are shallow, like 

 those between the intestinal and branchial arose. The distance between the external 

 orbital angles is little more than half the greatest width of the carapace (the spines 

 included), the proportion being in the larger specimen as 5 : 9, but in the other female 

 that distance is comparatively larger. As in Pot. {P arapotumon) spinescens, the post- 

 frontal crest is only represented by the two barely prominent, epigastric lobes ; the 

 mesogastric furrow between them is, however, somewhat deeper, and, instead of being 

 rugose, these lobes are distinctly granular, each being beset with ten or twelve rounded 

 granules. An oblique, shallow, though interrupted furrow or impression defines the 

 gastric region laterally ; on each side of it is another impression, of which the outer one, 

 on the branchial region, is larger than the other. The gastric and epibranchial regions 

 slope anteriorly down, so that the upper surface is somewhat concave behind the orbits. 

 The gasti'ic region is gramilar anteriorly, the granules being similar to those of the 

 epigastric lobes ; the swollen, antei'ior branchial lobes are also granular anteriorly and 

 near the antero-lateral border, but the granules near the latter are somewhat larger. In 

 the younger female they are less distinct. The rest of the upper surface is smooth, very 

 finely punctate. 



The front (PI. 33. fig. 60) resembles that oi Potamon spinescens, but its upper surface is 

 distinctly granular ; the granules are, however, smaller than those of the epigastric lobes ; 

 in the larger specimen the anterior border is half as broad as the distance between the 

 external orbital angles. The finely granulated frontal margin is notched in the middle 

 line, nearly as in Potamon spinescens, and the external angles are rounded; it makes riglit 

 angles with the lateral margins, so that the latter run at first parallel and then curve 

 outward. The upper orbital margin is also granular in the middle and externally, but 

 in the younger specimen it is still smooth, like the frontal border. The external orbital 



