I9I7-] S. Kemp : Notes on Crustacea Decapoda. 209 



The abdomen, though compressed, is not dorsally carinate. 

 The pleura of the fifth somite are narrowed and drawn out poste- 

 riorly. The sixth somite, measured dorsally, is a trifle more 

 than half the length of the carapace. The pleopods are excep- 

 tionally long, those of the first pair being about one and a half 

 times the length of the carapace. 



The telson reaches only a little beyond the middle of the 

 outer uropod. It is rounded above and sometimes bears a pair of 

 small spinules near the distal end. The apex, when perfect, is 

 seen to bear a single pair of lateral spinules which extend con- 

 siderably beyond the rounded median prominence. The outer 

 uropod is long and narrow ; its outer margin in front of the sub- 

 terminal spine is distinctly concave. 



Large specimens of L.tenuipes reach a total length of 65 or 

 70 mm. The eggs are small, about 0*55 mm. in length and 0*44 

 mm. in breadth. 



In examples from 15 to 30 mm. in length the rostrum is very 

 much shorter than in adults, not reaching beyond the middle of 

 the last segment of the antennular peduncle and with at most 

 only faint traces of teeth on the lower margin. The last abdom- 

 inal somite is proportionately much longer, being scarcely shorter 

 than the carapace in the smallest examples. In a specimen only 

 22 mm. in length the second peraeopods already closely resemble 

 those of adults, reaching beyond the antennal scale by almost the 

 entire length of the chela. The great length of the last three legs 

 is a conspicuous feature even in the smallest individuals. 



Leander tenuipes is evidently a very close ally of L. hastatus 

 (Aurivillius) ^ from the Cameroons. Aurivillius does not refer in 

 his description to the great length and slenderness of the last three 

 pairs of peraeopods, but it is clear from his figure that the species 

 possesses this character. A further examination of West African 

 specimens is necessary before the distinctions between L. hastatus 

 and L. tenuipes can accurately be determined. The African species 

 appears to differ in having 8 teeth on the basal crest of the ros- 

 trum, in the shorter fingers of the second legs which are usually 

 less than twice the length of the carpus, and in the greater length 

 of the sixth abdominal somite which is fully two thirds as long as 

 the carapace. According to Aurivillius' measurements the segments 

 of the second peraeopods show far greater variation in length than 

 in L. tenuipes, 



lyiving specimens of L. tenuipes are for the most part trans- 

 lucent with a slightly milky tinge. In adults the mandibular re- 

 gion is bright red and the rostrum is dotted with- carmine. The 

 lower antennular flagellum is carmine at the base changing to deep 

 mauve nearer the tip. There are a few very small red chromato- 

 phores on the segments of the large chelipede. On either side of 

 the abdomen there are red flecks at the points where the somites 



J Palaemon {Leander) hastatus, Aurivillius, Bihang till K. Sveiiska Vet.- 

 Akad. HandL, XXI\', Afd. iv, no. i, p. 27, pi. i\', figs. 7,-6. 



