8 9 



first joint with the outer distul process Ionger than the following joint and on its inner margin 

 furnished with 5 or 6 somewhat long spines and between these many very small spines (lig. 30); 

 the flagella even shorter than third peduncular joint. The antenna; with the inner flagellum a 

 little Ionger than the outer; both flagella unjointed with a few terminal setic. Maxillipeds with 

 the endopod only as long as the exopod, two-jointed; first pair of thoracic legs only as long 

 as the maxillipeds, with the endopod divided into feebly differentiated joints; second pair of 

 thoracic legs only half as long as the first, but with a trilobed branchia; third pair seemingly 

 consisting of a trilobed branchia, and fourth pair of a quite minute branchia. The two anterior 

 pairs of pleopods with both rami present and terminating in setóe, the three posterior pairs 

 without endopod and with the exopod naked. Fig. 3/ shows sixth abdominal segment with 

 uropods and telson, while fig. 3^ represents the distal half of the telson ; these two figures 

 show all details as to relative length, shape and spines so clearly that a description may be 

 omitted; vet the extreme difference between the armature of the distal part of the telson in 

 this forrn and in the larva of T. orientalis (figs. 2/1 — 21) may be pointed out, especially as the 

 larvse of these two species do not differ much from each other as to the stage of development 

 of antennse and maxillipeds, while the antennulae, the anterior thoracic legs and the posterior 

 pleopods are conspicuously more developed in the larva of T. orientalis than in that of T. 

 Agassizii. — The 3 larvse in the following stage are about 5.2 mm. long; they have the anten- 

 nulse, the anterior thoracic legs and the pleopods developed about as in the above-mentioned 

 larva of T. orientalis, while the apical part of telson has only a single pair (not as in the 

 previous stage (fig. 3^) two pairs) of minute spines; in other respects these larvae agree with 

 the former stage. 



Remarks. — Having at hand a large number of this species from the Pacific, I am 

 quite sure that it is T. Agassizii Ortm. But I am unable to decide with certainty if it is identical 

 with T. monacantha Ortm. (= T. lateralis H. J. H.), and I suppose that only an examination 

 of adult males of both forms can settle the question. But the adult male of T. Agassizii is 

 unknown to me, and of T. monacantlia from the Atlantic I have only a single female specimen ; 

 this differs from T. Agassizii in having the rostral process somewhat Ionger and distally distinctly 

 curved, but whether that feature is a specific character it is impossible to decide. Until further 

 evidence it may be advisable to keep the name T. Agassizii for the Indo-Pacific form. 



Euphausia Dana. 



This genus comprises a large number of species established by various authors, but I 

 learnt from the investigation of the copulatory organs of a large number of forms that some 

 of the species are far from well defined ; besides I have from various sources several hitherto 

 unknown species. It may be convenient to state here some of the results of my studies during 

 the last four years. 



Euphausia latifrons G. O. Sars differs in some features so much from all other species 

 that later in the present treatise I establish a new genus, Pseudeuphausia, for its reception. 



Euphausia Schotti Ortmann (Decapoden und Schizopoden, in Ergebn. Plankton-Exped., 



SIBOGA-EXPEDITIE XXXVII. 12 



