52 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



In nil of the other specimens al my disposal (stations 3251, 3252, 3506, 3541, 

 B( ring Strait, No. 6591 I the young have reached an advanced stage. As Lieberkind 

 writes, ii is the ventral, eversible stomach which is used as a brood pouch. The 

 number of young is in proportion to the size of the adult. In a specimen with R 

 43 mm., 42 young were counted but in the specimen figured (K 47 mm.) there were 

 probably 100, although they were no1 disturbed, or counted. As the egg develops 

 it naturally increases in size until the stomach becomes greatly distended, and the 

 walls in preserved specimens are quite thin. The young are crowded into the radial 

 pouches, and are found also in the central portion over the mouth. I did not find 

 them in the dorsal stomach, which confirms Lieberkind's observations, although 

 "at times the number of the eggs or the young was so great that they protruded 

 through the opening between the lower and upper part, forming a plug in the opening 

 (perhaps, however, this may be due to contraction on preservation). 15 



The young are frequently oriented with the actinal side against the stomach wall 

 and in some cases they may be seen through the tissue. In all the specimens except 

 that from Bering Strait, the young are separated — that is, are not joined to a central 

 mass of tissue as figured for L. arrtica. The larval organ, as a lappet of tissue, is 

 still conspicuous, and arises from an interradius back of the mouth plates. In the 

 Bering Si rait specimen (No. 6591) however the young are not quite so advanced, and 

 are anchored by a strand of tissue to a central mass, much as in L. arctica. 



In this case nearly half the young are outside the mouth, and the disk seems to 

 be arched in a natural manner as if to form an external brood chamber. This speci- 

 men is small (R 16 mm.) and it seems likely that it swallowed more eggs than there 

 was subsequently room for after complete development. Most of the large speci- 

 mens, known to be carrying young, have a few around the actinostome, although 

 it is possible these were expelled by contraction of the rays during preservation, 

 especially as the stomach in a few cases is partly extruded. 



I think however that during the later stages of development it is perfectly 

 normal for the young to be extruded from the stomach. This might well take place 

 for purposes of respiration, even if the actinal gastric space were sufficient to accom- 

 modate the increase in bulk due to growth. Possibly during the whole course of 

 development the eggs and embryos are given a periodic "airing." 



As stated above, specimens carrying young were taken at stations 3251, June 14, 

 l.v.Hl, bottom temperature 37. 5° F.; 3252, same date, bottom temperature 44.8° F. 

 (probably an error); 3506, July 29, 1893, bottom temperature, 32° F.; 3541, August 10, 

 1893, bottom temperature 36.1° F.; and at Bering Strait, July 14, 1879. The breed- 

 ing season extends probably from May through August. On June 14 the young are 

 large enough to leave the mother. The recorded temperature ranges from 32° to 

 Hs The first is usually low and the second unusually high for the locality, 

 judging by records of the preceding and succeeding soundings. (See list of stations".) 

 Thirty-six and thirty-seven degrees are probably near the optimum for successful 

 <\f. elopment. 



My observations confirm those of Lieberkind in respect to the entire absence of 

 food from the stomachs of all specimens carrying young. 



II Fra Dansk. naturh. Foren., vol. 72, p. 122. 



