302 Papers from the Marine Biological Laboratory at Tortiigas. 



connection between the maternal uterus and the embryo, corresponding 

 to the placenta in Mustelus acanthias." 



Since writing the aboNe, the following data have come to light from 

 Cuvier and Duvernoy's "Legonsd'AnatomieComparee" (1846). They say: 



In the eagle-ray, Narinari, there is developed only one oviduct, the left of 



which the first part has a round opening, and is folded lengthwise throughout its whole 



extent The second part has walls extremely thick and in great part 



glandular. The inner surface to a depth of 3 to 4 millimeters is composed of interlacing 

 filaments, forming an irregular mesh. Then comes a compact glandular layer, almost a 

 centimeter thick, in which are distinguishable parallel tubes, running straight from interior 

 to exterior. This glandular part is enveloped in a muscular layer clothed in peritoneum, 



Mr, Coles states in his recent paper (1913) that, in the female ,4, narinari 

 which gave birth to the four young above referred to, one uterus was much 

 larger than the other, Dr, Louis Hussakof, of the American Museum of 

 Natural History, at my request kindly examined this specimen, which has 

 been deposited in the Museum, and writes that the left oviduct only is 

 enlarged and villous, "the right being very small in comparison and with 

 the villous layer undeveloped." 



The young of Coles's ray above noted, four in number, were delivered 

 rolled up lengthwise, as is common in viviparous rays, but died quickly. 

 The various figures of plate v, but especially No. 11, show these young 

 shortly after birth, while figure 18, plate vii, is a photograph of one of these 

 taken after some months' preservation in formalin or alcohol. On com- 

 paring this young with an adult, it will be noted that its snout is shorter, 

 its forehead steeper, its eye and spiracle relatively larger, and especially 

 that its spots are fewer, particularly on the head. This specimen measured 

 286 mm. across the disk, was 171 mm, long, and the length of its tail was 

 634 mm. These young were spotted even on the head to some extent, but 

 Annandale's young specimen (not an embryo) of this ray was totally 

 devoid of spots (see fig. 17, plate vii). 



In connection with the breeding habits, attention is called to the fol- 

 lowing table showing the length and width of the fish and the length of the 

 claspers in all the males taken by me: 



From this table the conclusion is readily drawn that only the last 

 specimen was sexually mature. Furthermore, comparison of these rays 

 shows that, size for size, males of Dasyatis say and hastata have much smaller 

 claspers than Pteroplatea maclura. Only two other naturalists seem to have 

 noted this interesting point. Ruppell (1835) remarks that these organs are 

 small in his Red Sea specimen, and he therefore concludes that is a young 



