COPEPODA 13 



imens varied from 27 to 4-5 mm. I have found the same to be the case in several samples from the 

 west coast of Greenland. 



In a sample from Jakobshavn I found 100 specimens (f?) varying in size from 3-3, 3-5, 3-8 to 

 4-1 and 4 specimens 4-6 to 53 mm. long; a young female from the same sample measured 3-9 mm., 

 19 young ones measured about 3 mm. From Ingolf St. 28 f? of size from 3-5 to 5-1 and j'oung spec- 

 imens from 3-5 to 4-8 were taken. 



By comparing the length of the urosome and anterior portion in specimens from different 

 localities and of different size etc. it was quite impossible for me to find any character of value. In 

 specimens of f? from the west coast of Jutland (Thyboron, Thor '7/3 04) the head was certainly more 

 produced than in specimens taken 73° L. N. 8° L,. E. by Johannes Petersen, but in the former 

 the caudal rami were scarcely as long as wide, and a little longer than the anal somite, and in the 

 latter distinctly 2-i as long as wide. In 3 of the mentioned specimens from Denmark the antennulae 

 reached three segments beyond the tip of the urosome, but in 2 other specimens two only ; in specimens 

 from Spitzbergen (c. 3-4 mm) they extended three segments beyond the end of the urosome, but in a 

 big specimen from Greenland (53 mm) with the head even less produced than the specimens from 

 Spitzbergen the antennulae extended only two segments beyond the urosome. 



As far as the shape of the head is concerned the differences between the different types are 

 better marked in the males than in the females; as far as the characters found in the fifth pair of 

 legs are concerned I first tried like Mrazek to find a character in the variations of the spinulation 

 of the inner margin of the second basipodite, but like him without success. 



In Sars' figures of C. /hitnarchims the pes V does not extend to the end of the abdomen; 

 in none of my specimens the pes V is so short as figured by Sars; in all my specimens they extend 

 to or almost to the end of the abdomen. In all the examined males (from Denmark, Greenland or Spitz- 

 bergen) except in a single one from Denmark, the Ri III sin. reached beyond the middle or almost 

 to the end of Re II. In a single specimen from Denmark the Re II sin. was 17 as long as the 

 Re III, but in most other specimens the Re II was 1-4 or 1-5 as long as Re III; the last segment 

 differs from Sars' figures by a more or less marked rounded protuberance basally and inwards. 



Scott (1905), followed by Pearson (p. 5), has accepted Sars' two species, but most authors 

 agree in regarding the proposed characters as insufficient f. inst. Wolfenden (1904 pp. 126—127), 

 Farran (1905 p. 30) and Gough (1905). Mrazek has (1902 pp. 502 — 506) without knowledge of 

 Sars' point of view tried to solve the question. Without result he tried to find characters in the 

 dentation of the inner margin of the first basipodite of the fifth pair of legs. He writes p. 504: 

 »Etwas konstanter erwiesen sich die Langenverhaltnisse der vorderen Antenne. Die Lange derselben 

 ist der L,ange des Korpers umgekehrt proportionell. ; He also found differences of some value in the 

 armature of the legs, and the relation between the length of the different parts of the body; but he 

 rightly thought, that a detailed study of a lafger material, consisting of specimens, originating from 

 a different region of the ocean with statistical methods of studying the limit of variation, would scarcely 

 solve the question, without at the same time studying material from well defined geographic regions. 

 The question ought soon to be properly investigated, for if Cal./ininarchicus and helgolandiciis should 

 really be proved to belong to two different species, a good deal of the vast amount of knowledge 



