246 Memoir Sears Foundation for Marine Research 



or posterior part of each pectoral often with 1-4 black or dark brown ocellar spots 

 edged with white and var\nng from round to oval; sometimes 1—2 smaller ones nearby; 

 size, arrangement and number of these spots varying from specimen to specimen; some- 

 times each pelvic with a similar ocellar spot. Each side of snout in front of eyes with a 

 whitish translucent area. Lower surface usually white but marked with irregular pale 

 brownish blotches of various sizes'" on posterior part of disc and along tail of some 

 specimens. 



Size. Specimens so recently hatched that their abdomens are still more or less swol- 

 len with yolk range from about 1 12-127 rn^n in length, apart from whatever remnant 

 of the embryonic caudal filament may still persist. In a male of 665 mm the claspers 

 reach about to the tips of the pelvics; in one of 715 mm they extend about one-third of 

 the way from the axils of the pelvics toward the tip of the tail ; and halfway in one 8 i o mm 

 long. All of the males are sexually mature by the time they have reached a length of 

 about 750 mm, some by 620 mm.*" The longest female we have seen measured 806 mm, 

 the longest male 834 mm ; the maximum recorded length is about 43 inches ( i ,090 mm).*^ 

 On the average, males about 20 inches long weigh 2 pounds; 30 inches, 7 pounds; 

 32 inches, 9 pounds. Females about 20 inches long weigh 2 pounds; 25 inches, 4V2 

 pounds; 28 inches, 6^2 pounds. ^^ 



Developmental Stages. The greenish brown or brownish olive egg cases are about 

 55-86 mm in length by 35-52 mm in breadth, excluding the horns, and northern spe- 

 cimens average larger than southern ones.*^ The end with the shorter pair of horns is 

 weakly concave, that with the longer horns straight or weakly convex and more or less 

 ragged. The horns are strongly flattened and each is described as having a slit on its 

 outer edge near its tip.** The longer pair of horns on egg cases that have been laid is 

 usually about 1.5 times as long as the shorter pair and about 1.5 times as long as the 

 egg case, but the extreme tips are likely to have been broken off. The outer margin, 

 close to each of the shorter pair of horns of newly laid cases, bears a short slender spur, 

 the edge of which, like the remainder of the lateral border, is fringed with a series of 

 silky filaments that are tangled and matted together. But these as well as the spurs are 

 so easily torn off that only tufts remain here and there on cases that have been deposited 

 for more than a brief period. No doubt the filaments serve as anchors.*^ 



Embryos ready for hatching already show the distinctive characters of the species 

 so clearly that they are easy to identify. 



79. 15 by 15 mm to 3; by 74 mm in one specimen. 



80. This is the case in the Block Island region, according to the Bingham Oceanographic Laboratory. 



8 1. A maximum length of six feet credited to this species by Hildebrand and Schroeder (Bull. U. S. Bur. Fish., 43 

 [i], 1928: 58) actually referred to R.lae'vis. 



82. We are indebted to the Bingham Oceanographic Laboratory for these data on maximum recorded lengths and 

 on length-weights. 



83. 75-86x44-52 mm from Nova Scotia (Vladykov, Nat. canad., 63, 1936: 216); 66-70X45-45 mm for two from 

 Provincetown, Massachusetts; and 64-70X 35-42 mm from New York (Breder, Copeia, 1937: 182). 



84. These slits, recorded by Wyman (Mem. Amer. Acad. Arts Sci., N. S. 9 [2], 1864: 31) are not visible on the pre- 

 served specimens we have seen. 



85. For an account, with exellent illustrations, of the lateral spurs and filaments and of the embryonic development, 

 see Wyman (Mem. Amer. Acad. Arts Sci., N. S. 9 [2], 1864: 32, 33, fig. i, 2-10). 



