﻿PYCNOGONIDA. ^r 



Distribution. The species is circmnpolar, and besides it follows as well the American as 

 the European shores far southward, thus beiuij one of the most widely spread and most common 

 Pycnogonida on deep water. 



i6. Nymphon tenellum (i. ( ). Sans. 



N\'mplion tenellum vSars, Pycnog. bor. arct., iSS.S, jx 353. 



— - Idem, Pycnoo-onidea, iiSgi, p. 109. PI. XII. Fig. i, i a-h. 



Occurrence. The Ingolf-stations are: 7, 2S, and 44, showing it to be found in the northern- 

 most part of the Atlantic and in the south of the Davis Strait in depths from 420 to 600 fath. 



Distribution. The species had hitherto onh' been found In- Sars in the sea off the Fin- 

 mark, and consequently this author took it to be a genuine arctic form ; the three stations gi\-en here, 

 carr\- the species much farther south and west, alwa>-s on very deep water. 



17. Nymphon robustum Bell. 

 PI. III. Fig. 23-^24. 

 Nymphon robustum Bell, Account Crust., 1855, p. 409. PI. XXXV. F'ig. 4. 

 Chaetonymphon robustum Sars, Pycnogonidea, 1891, p. 115. PI. XII. Fig. 3, 3 a-d. 

 Nymphon hians Heller, Crust. Pycnog. Tunic, 1875, p. 41. Tab. V. Fig. 3— 5. 



The species varies ver\' much, especially as to size; thus a grown male has measured 23""", 

 and an unripe female 19,5""", while on the other hand grown males of 11""" are not rareh' met. These 

 differences for a long time induced me to suppose two or more sjDecies to be hidden under tlie old A'. 

 robustnin, and so I began to stud\- the se\eral small and large specimens in their mutual contrast, 

 and thought in the arnu\tm-e of the fourth and fifth joints of the ovigerous legs of the male to have 

 found a sure criterion. I had, however, soon to give up the thought of the systematic importance of 

 this armature; but nevertheless I have partly rendered it here in pi. Ill, fig- 23 and 24, as it seemed 

 to me to give a good idea of tlie powerful development and the different shapes and positions as- 

 sumed by the bristles of the legs for the attaching of the eggs and \ouug; it is, however, also to 

 be remembered that N. rohiisfiiiii is likeh' to Idc the Pycnogonid, on the male of which the young 

 are most firmly attached , and cling for the longest time. 



r)ccurrence. The Ingolf-stations are: 3, 4, 15, 41, loi, 1013, 105, 115, 116, 126, 138, 139, 140, 141, 

 143. According to tliis series of stations it has most frequeutl\- Iteeu taken in the west and smith 

 parts of the Norwegian Sea, and some wa\- into the Atlantic; single specimens have been taken in 

 the Greenland Sea and the Dennuark Strait. The depths were mostly between 300 and Soci fath., only 

 once below 100 fath. viz. 86 fath. 



In the Zoological Aluseum it is found from the Cireenlaud Sea: 70' 26' Lat. N. (Deichmann); 

 72 26' Lat. N. 19" 35' Long. W., 105 fath. (idem); 72 53' Lat. N. 20 36' Long. W. , 96 fath. large stones 

 (idem); vScore.sby vSound 3 — 25 fath. (idem); from the Davis vSlrait, 66" 16' Lat. N. 25 ' 20' Long. \V. , 327 



