MACRUROUS DECAPODA OF THE SUDANESE RKD SEA. 393 



a three-jointed mandibular palp. Spence Bate (1888, p. 784) makes no 

 mention of the number of joints in the palp but merely remarks on its 

 "extreme tenuity." The question is of great importance in connection with 

 the characters of the genus Leander. The type of the latter genus is 

 L. erraticus, Desmarest, identified by Spence Bate and later authors with 

 L. natator, M.-Ed., which, as mentioned above, Stebbing has shown to be 

 identical with I,, tenuicomis of Say. Stimpson also gives L. natator as the 

 type species. It follows, therefore, that the type species of the genus 

 Leander has a two-jointed palp, and if the number of joints in the mandibular 

 palp be considered of generic importance, it is the three-jointed palp species 

 which must be transferred to a new genus. 



Palcemon torensis, Paulson, cannot be identical with L. natator, M.-Ed., as 

 surmised by Nobili, since Paulson distinctly figures the mandibular palp 

 as three-jointed. On the other hand, Palcemonella gracilis, Paulson, is a 

 species of Leander with a tw r o-jointed mandibular palp. 



These remarks will serve to show the pressing need for a revision of the 

 genera and species of this family. 



Distribution. Widely distributed in the Atlantic, Mediterranean, Indian, 

 and Pacific Oceans. 



Leander concinnus (Dana, 1852, p. 587, pi. 38. fig. 10). 



Leander Imtyioarpus, Oi'tmann, 1891, p. 516. 

 Leander coneimvus, De Man, 1897, p. 765. 

 Leander concinnus, De Man, 1902, p. 807. 



Locality. Station I. A, 23 specimens, the largest 38 mm. in length. 



Remarks. The rostrum in the majority of the specimens has the form 

 shown in Dana's figure 10 b. There is in all the specimens but a single 

 tooth behind the orbit. This is followed by from 4-6 teeth more or less 

 equidistant!)- placed on the proximal part of the rostrum. The distal part is 

 upcurved slightly, and usually devoid of teeth with the exception of a small 

 one almost at the extreme apex, giving the latter a bifid appearance. In two 

 specimens the apex is trifid,and in one of the remaining specimens there is a 

 single tooth on the distal part of the rostrum half-way between the proximal 

 teeth and the apex. Below, the rostrum bears from 3-5 teeth. The rostral 

 formula may therefore be represented as follows : — 



1 + ( 4-C) + (0-1) + bifid (trifid) :i pex 

 3 5 



This species, like the preceding one, has the palp of the mandible two- 

 jointed. 



Distribution. New to the fauna of the Red Sea. Fiji (Dana) ; East Indian 

 Archipelago (De Man). 



LINN. JOURlS'. — ZOOLOGY, VOL. XXXIV. 30 



