6 Fishery Board for Scotland. 



Day states that he had received a pnrse of Raia alha. The purse 

 measured 16 inches x 64- inches. It is possible that the parent of 

 this purse was macrorhyncMis. 



The following paragraph is extracted from Beard's paper : — "The 

 author inclines to the view that the purse of a skate is partly formed 

 in the oviduct before the egg leaves the ovary. Fertilization must be 

 effected in the upper limit of the oviduct. For some weeks at least 

 the egg undergoes development within the maternal oviduct, and there 

 it normally lies till the first traces of the embryo appear. It is then 

 laid by the mother skate, and undergoes its subsequent long develop- 

 ment at the bottom of the sea. i^ever more than two eggs, one in 

 each oviduct, are found in a single skate." 



Bugnion says that the test of the egg of the skate is formed in a 

 glandular thickening of the oviduct {glande nidamenteuse). At this 

 part, the cavity of the organ is dilated, flattened, and exhibits four 

 horns or prolongations in which the four points of the egg are 

 moulded. There is only one egg in the oviduct in the process of 

 development. Impregnation of the egg is effected in the superior 

 part of this organ before the test is formed. The freshly laid egg does 

 not enclose an embryo, but only a little scar similar to that of the egg 

 of the domestic fowl before inciibation. In fifteen days after the 

 extension of the egg, the embryo measured 7 mm. in length. 



While there seems to be no doubt that the egg is usually extruded 

 while the embryo is in a very early stage of development, it has been 

 asserted b}^ fishermen that little skate have been found inside purses 

 taken out of the mother. 



Eggs of skate have, Mr. Thomson informs me, been taken in 

 considerable numbers on ground 16 miles south-south-east of 

 Aberdeen by the trawl towing off the shoal water on Aberdeen Bank. 



EXPLANATION OF PLATES. 



Plates L, II., III., IV., V. 



Fig. 1 . Transverse section of purse of Raia batis ; approximately natural size. 

 yy, yellow yolk (ovum) ; try, white yolk. 



,, 2. Purse of Raia batis, natural size. 

 ,,3. ,, Rata fullonica, ,, 

 ,,4. ,, Raia circularis, ,, 

 ,, 5. ,, Raia radiata, ,, 



,, 6. Abnormal purse of Raia batis, natural size. 



,, 7. Purse of Raia macrorhynchus (dried specimen), natural size. 

 ,,8. ,, Raia clavata, natural size. 

 ,,9. ,, Rfiia oxyrhynchiis, ,, 



,,10. ,, Raia blanda, reduced. (After Holt and Calderwood). 

 ,, 11. ,, Raia mierocellata, ,, ,, ,, 



,, 12. ,, Raia maculata, ,, ,, ' ,, 



