1886.] MR. R. COLLETT ON BAL.ENOPrERA BOREALIS. 2.")9 



The corpus emerges almost without any transition from the neck, 

 and has a lenoth ofabout 19 millim., making the animal's total length 

 about 25 millim. It is perfectly cylindrical, and has a regular 

 breadtli of about 3| to 4| millim., which is thus to the total length 

 as 1 to about 6^. 



Males and females were intermixed and seemed to be present in 

 equal numbers. The two sexes do not appear to diifer in length, 

 colour, or general appearance ; though the males were at the first 

 glance distinguishable on account of the two projecting folds in the 

 skin encircling the outer orifice of the genitalia. 



The females were all full of myriads of eggs : these were of normal 

 structure, and measured about 0'135 millim. in length; no trace of 

 the row of spines which appears on the head of the embryo of the 

 other species could he found when magnified GOO times. Neither 

 were spiral threads to be seen, as described in EchinorhyncJtus proteus 

 (Zeitschr. f. wiss. Zool., Bd. xiii. p. 418). 



It cannot of course at present be stated whence B. horealis 

 obtains the larvae of E. ruber. As the species is decidedly different 

 from E. hrevicollis, described by Malm from B. sibbaldi, it is not 

 probable that both species get their parasites from the same crus- 

 tacean. We know that Euphausia inermis (a Thysanopod) is the 

 species from which B. sibbaldi probably exclusively obtains its food 

 in the summer months, and it is therefore not improbable that Echino- 

 rhynchus brevicollis passes through its first stages with this species. 



Whether Calanus finmarchicus is the first host of E. ruber can 

 only be conjectured as a possibility. It seems, however, more 

 probable that a somewhat larger crustacean, which perhaps consti- 

 tutes the food of this Whale at other seasons of the year, is the true 

 transporter of this parasite. 



Its diagnosis will be as follows : — 



E. RUBER, n. sp. Total length 2.5 millim.; proboscis with about 4 

 rows of spines, rostellum with 10-12 rows. Neck shorter than the 

 transverse diameter of the body, thread-like. Corpus short, emerging 

 abruptly from the neck. Colour in adult brick-red. 



XI. Time of Capture. 



It has been previously stated, that in 1882 B. borealis first 

 became the object of general capture, especially at the newly founded 

 estabhshment at Soroen, near Hammerfest, and it appears to " close 

 the land" about there every year, although in varying numbers. 

 In previous years the first specimen, according to Capt. Bull, 

 was captured in the beginning of June. The 24th of June was about 

 the best period for catching them, while after the 8th July thev 

 gradually disappeared, when other species generally appeared {B, 

 musculus and B. sibbaldi). 



This year (1885) B. borealis coasted the land along the whole 

 of Finmark, and formed such a considerable portion of the 

 " Fishery," that it surj)assed the number of all other species com- 

 bined. 



