REPORT O^ THE SCHIZOPODA. 97 



consi.st merely of three thin memljrauous plates, of which the median is the longest, and 

 quite unarmed, whereas the outer one exhibits two short spiniform bristles at the apex ; 

 the inner plate is very narrow, and may strictly be regarded as the secondary lobe of the 

 principal plate. The appendages to the second pair of pleopoda (see fig. 21) are more normal 

 in structure, but rather small, projecting slightly beyond the apex of the principal plate. 



The telson (see fig. 22) is of the usual slender form, with three pairs of small dorsal 

 denticles. The subapical spines (see fig. 23) are rather strong, and have the inner edges 

 finely denticulate. 



Habitat. — The specimens procured during the Exj)edition were collected at the surface 

 of the sea in the following localities : — • 



The distribution of the species would accordingly seem to be restricted to the 

 Australian Seas and those of the Indian Archipelago. 



Genus 2. Thysanopoda, Milne-Edwards, 1830. 

 Thysanopoda, Milne-Edwards, Ann. d. Sci. Nat., t. xix. 



Generic Characters. — General aspect as in Euphaima. Flagella of both paii's of 

 antennse greatly elongate. Exognath of second pair of maxillae very small. Maxillipeds 

 and anterior pairs of legs nearly as in Euphausla. Penultimate pair of legs distinctly 

 developed, and of the same structure as the preceding ; last pair with the eudopod 

 obsolete, but having a well-developed exopod. All the true gills provided with an 

 interiorly lient branch ; the two posterior pairs rather complex in structure, last pair 

 much the larger and richly arborescent. Luminous globules as in Euphausia. 



Remarks. — The present genus — that first established in the family — was founded on 

 a form procured from the Atlantic and described by Milne-Edwards under the name of 

 Thysanop>oda tricuspid ata. Neither this t}"pical species, nor other forms strictly 

 belonging to the present genus, have been recorded by any subsequent naturalists ; for 

 all the forms since described as Thysanopods ought, in my judgment, to be referred to 

 different genera of the family. The present genus — in the restriction here adopted — is 

 chiefly characterised by the penultimate pair of legs being fully developed and having a 

 structure quite similar to that of the preceding pairs, whereas in the last pair the endopod 

 is wholly wanting, the exopod only being of normal develojjment. Moreover, in the 



(ZOOL. CHALL. EXP. PART XXXVII. 1885.) Oo 13 



