— i5 — 



but judging from various particulars on his two drawings 

 I am apt to think that he had examined specimens of 

 Euphausia lucem H. J. H. 



In No, 42 of this Bulletin I described a large adult 

 female from the Monaco collection of T. pectinata Ortm. 

 The Agassiz material from the East Pacific contains a good 

 number of adult specimens of a form, which is conside- 

 rably smaller than the specimen from the North Atlantic 

 and differs in having the frontal plate nearly triangular or 

 only narrowly rounded at the front end, while this plate 

 is very broadly obtuse in the Atlantic specimen. During 

 years I considered the Pacific form as a separate, though 

 closely allied, species, but recently I received a large and 

 a considerably smaller male, both adult, together with 

 some adult females captured in 1910 by the Prince of 

 Monaco, and an examination of the copulatory organs 

 does not reveal any difference in these most important 

 organs between specimens from the Atlantic and the 

 Pacific. As the only real difference between my speci- 

 mens from the two oceans is that the frontal plate is less 

 produced and more broadly obtuse in the Atlantic speci- 

 mens than in those from the Pacific, I am forced to refer 

 all to T. pectinata Ortm. 



a. Carapace without any distinct cervicat groove. 

 Sixth abdominal segment longer than the fifth. 



The following species belong to this group : T. tricus- 

 pidata M. Edv., T. cristata G. O. S., T. monacantha Ortm. 

 (= T. Agassi\ii Ortm.), T. œqualis H. J. H., T. obtusi- 

 frons G. O. S., T. pectinata Ortm., T. microphthalma 

 G.O. S., T. acutifrons Holt andTatt., T. orientalis H. J. H. 

 In the five first-named species the carapace has a denticle 

 on the lower margin towards its posterior end, while in 

 the four other species no such denticle is found in adult 

 and subadult specimens, though present in very young 

 specimens. 



(210) 



