23 



Key to the species obtained by this expedition. 



a. Posterior margin of carapace smooth. Carina of the abdominal terga 



deeply notched. Orbital notches not subdivided Carpenteri (Alcock) 



aa. Posterior margin of carapace spinulose. Carinae of the abdominal 

 terga entire. 

 6. Orbital notches subdivided. One single rostral tooth. Median 



spine of 5 th abdominal tergum not smaller than the 4 th . typhlops Heller 

 6b. Orbital notches not subdivided. Two rostral teeth. Median spine 



of 5 th abdominal tergum distinctly smaller than the 4 th . 6accatus Sp. Bate. 



It is for the first time that species of this genus are recorded from the Indian Archipelago, 

 for which fact we are indebted to the "Siboga" expedition: probably still a few other species 

 will afterwards prove to occur in these seas, especially Pol. granulatus Fax., gib6us (Alcock), 

 laevis (Sp. Bate) and o6scurus (Sp. Bate). 



Pol. Carpenteri (Alcock) was taken at the great depth of 1122 fathoms, almost as 

 deep as the type from the Bay of Bengal; Pol. typhlops Heller was captured at depths of 

 158 and 285, Pol. baccatus Sp. Bate between 218 and 284 fathoms. 



1. Polycheles Carpenteri (Alcock). (PI. I, Fig. 



&• o) 



Pentaclieles Carpenteri A. Alcock, Annals Mag. Nat. History, March 1894, p. 235 and in: 

 A descriptive Catalogue of" the Indian Deep-Sea Crustacea, Calcutta, 1901, p. 174; Illustrations 

 of the Zoology of the Investigator, Crustacea, PI. X, Fig. 1. 



Stat. 126. July 20. 3°27'.iN., i25°i8'.7E. 2053 m - Bottom hard (Traces of fine dark, hard 

 sand). 1 adult male. 



This male has just the same size as the only female on which this species was founded. 



The length of the carapace, measured in the middle line, is half a telson-length shorter than 



the abdomen and this length is in proportion to the greatest width as 4:3; the greatest width 



is one-third the length of the whole body. The acute spine that arises from the frontal wall 



of the carapace in the middle line, is small, does not reach to the level of the upper surface 



of the carapace and is curved backwards. The formula for the spinature of the left 



7 5 



border is k for that of the right 3. The quite smooth and narrow, posterior margin of the 



carapace is more concave than in Figure 1 of the "Illustrations", its concavity is as large 



as in Fig. 2 of the same Plate X. The rounded outer angle of the right orbital notch is 



unarmed, that of the left carries a short sharp spine directed upward: the occurrence of this 



spine is evidently abnormal. The eye-peduncle carries a small sharp tooth or spine, directed 



a little outward, on the frontal border, considerably nearer to the outer than to the inner angle 



of the orbital notches; the shape of the eye-peduncle is characteristic. It is namely deeply 



grooved above posteriorly, so that the posterior end that carries the cornea, is distinctly separated 



from the rest as a prominent, nearly globular tubercle ("Illustrations", Fig. 1^). 



The 2 nd to 5" 1 terga carry a few small granules on each side of the middle line, near 



