606 THE VOYAGE OF H.M.S. CHALLENGER. 



compressed than the preceding, dorsally arcuate and posteriorly produced to a point. 

 Sixth somite longer than the fifth. 



Telson longer than the sixth somite, narrow, tapering, dorsally flattened and laterally 

 compressed, longitudinally armed with a few solitary spinules and tipped with long and 

 short rigid spines. 



Ophthalmopoda short and pyriform, supported on a small pedicle, having the 

 ophthalmus proportionally large, and furnished with an ocellus that, in the typical species, 

 Pandalus annulicomis, is slightly elevated and surrounded by the dark pigment of the 

 ophthalmus. 



First pair of antennae longer than the rostrum, carrying two flagella, and furnished 

 at the base with a stylocerite that is rounded at the apex, and but half the length of 

 the joint which carries it. 



Second pair of antennse rather longer than the animal and carrying a scaphocerite 

 that is nearly as long as the carapace, narrow and slightly tapering to the distal 

 extremity, where it is rounded on the inner and furnished with a sharp tooth on the 

 outer distal margin. 



Mandibles having the psalistoma and molar process distinct, and supporting a well- 

 formed three-jointed synaphipod. 



First pair of siagnopoda small and three-branched. 



Second pair having the outer or mastigobranchial plate produced posteriorly, slender 

 and filamentous. 



Third pair having the ecphysis of the basisal joint produced anteriorly, and tapering 

 to a slender process. 



First pair of gnathopoda having the carpos and propodos reflexed, and carrying a 

 long basecphysis. 



Second pair pediform, without a basecphysis, and carrying only the rudiment of a 

 mastigobranchial appendage similar to those of the pereiopoda. 



First pair of pereiopoda long, slender and simple. Second pair unequally long, 

 slender and chelate, having the carpos long and multiarticulate. Three following pairs 

 tolerably robust and terminating in a strong, short dactylos. 



Pleopoda biramose and foliaceous. 



The branchiae consist of eleven pairs of plumes and may be tabulated as follows : — 



Pleurobranchise, . . . 1 1 1 1 1 



Arthrobranchise, . . . ... 1 1 1 1 1... 



Podobranchise, . . . 1 ... 



Mastigobranchial, . . . lr rrrr... 



hi k 1 m n o 



Geographical Distribution. — The type species, Pandalus annulicomis, Leach, is- 

 Europeau, and mostly found on the French and British coasts. Milne-Edwards records a 



