.is BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



from station 2847, 48 fathoms, has K 39 mm.; from station 2845, 42 fathoms, 30 mm.; 

 from station 2851, 35 fathoms, 39 mm.; from station 3259, 25.5 fathoms, 33 mm.; 

 from station 3265, 38 fathoms, 37 mm. Tims the maximum size ranges roughly 

 from 24 mm. to 39 mm., the smallest being from (is fathoms. The specimens from 

 stations 3213, 3214, 3215, 3217, 3218 are also small, and are all within these extremes — 

 the majority having K less than 30 mm. 



The specimens from Popoff Strait, the Shumagin Islands, and Agattu are not 

 typical. They are small and the spinelets are more widely spaced than in average 

 deep-water examples. Crossed pedicellarise are few on all spines. 



Specimens from stations 3265, 3266, and 3291 have given considerable trouble 

 on account of their variability and general resemblance to L. arctica. Those from 



5 are referable to hylodes except one which if considered alone would be regarded 

 as L. arctica forma beringensis with rather slender spines, and is so recorded. Speci- 

 mens from 32(HJ are like this single example from station 3265 except one which is 

 referable to hylodes. Four have been recorded as aberrant arctica. Out of 28 speci- 

 mens from station 3291, one is referable to hylodes and the others to L. arctica forma 

 beringensis with unusually slender, but fairly well spaced spines. Other specimens 

 of arctica which approach hylodes are found at stations 3242 and 3262. Typical 

 hylodes is very distinct from arctica and ranges, through various small races, into 

 Japanese waters. It is found in its most typical form south of the Alaskan Penin- 

 sula, west of Afognak Island. Whether these aberrant specimens of arctica from the 

 region of Bristol Bay are intermediates, or the results of crossing with hylodes, speci- 

 mens of which were found in the same bottles (as stations 3265, 3266, 3291) must 

 remain undecided. It is probable that hylodes does not range far into southern 

 Bering Sea. 



Anatomical notes. — The skeleton is essentially like that of arctica, with sur- 

 prisingly little difference when allowance is made for the disparity in size. In 

 hylodes the abactinal skeleton consists almost entirely of primary, mostly 3-lobed 

 plates with relatively few intermediate ossicles such as multiply in large examples 

 of true arctica, or its southern Bering Sea form. Corresponding to the first 10 

 inferomarginals there are 29 or 30 adambulacrals. The series of actinal plates of 

 a specimen from station 2847 with R 22 mm. extends along the ray about two- 

 thirds K from center, or to th< twelfth inferomarginal (a little over half length of 

 ray measured on sid< . 



The gonads are fully developed in an example with R 17 mm. from station 2856. 

 Tin \ open on the ventral surface, close together, on either side of the interradial 

 furrow, and on a level with the actinal plates, or a trifle higher. The aperture is at 

 the summit of a conspicuous thick papilla, when the products are mature, and is 

 often guarded by a large straight pcdicellaria. The testes extend fully half the 

 length of ray and consist of a number of relatively slender, lobulated lobes, while 

 ,1m> ovaries are shorter, more compact, with a few subsphericaJ lobes, or without 

 In a specimen from station 3215, May 21, temperature 38.5° F., the gonads 

 are not mature, although ■ . ppear to be on the way to maturity. Those from 

 ■ ll ""' -•"'• temperature 39.8° F., have good-sized gonads, apparently 

 not yet mature, however. In examples from station 2847, July 31, temperature 



