NO. 1341. AMPHIPODA FROM COSTA RICA— STEBBING. 997 



the clasping margin ("palm," Sp. Bate) of the hand in the second pair of feet la 

 uniformly convex, the last pair of feet is slender and sindlar to the preceding. Sub- 

 sequently the antenna- become thickened, two, three, or four of the first joints of the 

 flagellum are fused together, the palm of the hand acquires a deep emargination 

 near its inferior angle, and the intermediate joints of the last pair of feet become 

 swelled into a considerable incrassation. No museum-zoologist would hesitate about 

 fabricating two distinct species, if the oldest and youngest sexually mature males 

 were sent to him without the existing intermediate forms. In the younger males of 

 Orchrsiia Tncumtinga, although the microscopic examination of their testes showed 

 that they w^ere already sexually mature, the emargination of the clasping margin of 

 the hand (represented in fig. 50) and the corresponding process of the finger, are 

 still entirely wanting. The same may be observed in Cerapus ami f'nprplh, and 

 probably in all cases where hereditary sexual differences occur. 



A footnote saj's that tig-. 50 represents the second gnathopod ol" the 

 male, and %. 51 that of the female, of Orchestia tncuratlnga. 



The original German edition adds the letters " n. sp." after the men- 

 tion of O. tiicirratwga. For the translation Miillor himself supplied 

 corrections of printers errors in the original. Yet we lind CA tueu- 

 rauna and O. tucuratinga left side b}^ side both in the text and index 

 of the English edition. If they are one and the .same species, the 

 remarks on the differences between the young and old males are need- 

 lessly repeated. If the}^ are distinct species, not the smallest character 

 is assigned by which tlie}^ can be distinguished. No museum zoologist 

 could have made a w^orse muddle. Nothing is said about the first gnath- 

 opods of either sex. If these were left unexamined, the species might 

 belong to Ot'chestoidea or Talorehestia I'ust as well as to OrcJiestla. 



A general resemblance in the second gnathopods of the Costa liican 

 species to those figured by Fritz Miiller excited a hope that his descrip- 

 tion might be supplemented from the specimens now in hand. The 

 hope was dissipated by more exact comparison. Though the young 

 males showed the uniforml}^ convex palm and smoothly concave finger- 

 margin of the second gnathopods, combining with these the common 

 youthful characters of slender second antennie and slender hind pcra^o- 

 pods, the older males and the females did not fall into line with the 

 species represented by Midler. The length, compared with the l)rea(lth 

 of the large hands, is much greater in the present species than in his, 

 and the palm is less convex. Also in the delicate second gnathopod 

 of the female there are several differences, most easily seen ])y a com- 

 parison of the figures. lu the species here descril)ed the second joint, 

 instead of being oval, has a straight hind margin and sinuous front 

 one, the fifth and sixth joints are narrower than in Miiller's species, 

 and the rounded apex of the sixth is much more produced beyond the 

 minute chela-forming finger. It may be added that, though the pedun- 

 cles of the second antennsB. are greatly thickened in the large males, 

 the initial joints of the flagella show no additional fusion, nor is the 

 thickening of the middle joints in the hind peraiopods especially 

 conspicuous. 



