of the Fishery Board for Scotland. 



193 



The following is a description of the ovaries of an eel 90 cm. (36 

 inches) in length : — The right ovary commenced at a point, 3'2 cm. 

 behind the diaphragm, and 5*5 cm. posterior to the insertion of the 

 pectoral fin. The abdominal portion of the ovary, that is, from its 

 anterior end to the level of the aims, was 32 cm. in length ; the caudal 

 portion (Ro. fig. 4, PI. VII.) ended at a distance of 4*4 cm. behind the anus. 

 On the inner side of the caudal portion was an accessory ovary (pars re- 

 currens ovarii) (Rpr.). The pars recurrens was not separate from 

 the caudal portion in all its extent, but was united with it at its posterior 

 extremity (x.), for a distance of 14 mm. It had a length, inclusive of 

 the fused portion, of 29 mm. 



The right ovary was 4 mm. wide at its anterior extremity ; it rapidly 

 increased in breadth till at a distance of 3 '5 cm. from the anterior end 

 it measured 25 mm. in width. The same width was retained for a 

 distance of 11*5 cm. The ovary then gradually diminished in width, 

 until at the level of the anus it was 13 mm. wide. The caudal portion 

 narrowed from the anus backwards, and at its posterior extremity had 

 a width of 6 mm. The pars recurrens, at the point of union with the 

 caudal portion, was 6 mm. wide, and at its anterior extremity 4 mm. 

 wide. 



The left ovary began at a point 6*2 cm. from the diaphragm, that is, 

 3 cm. behind the right ovary, and 8 2 cm. from the insertion of the 

 pectorial fin. The length of the abdominal portion was 19-5 cm. The 

 caudal portion (Lo.) extended to a distance of 8 cm. behind the anus. 

 As in the case of the right ovary, there is an accessory ovary (Lpr.) on 

 the inner side of the caudal portion. The pars recurrens was united to 

 the posterior extremity of the caudal portion for a distance of 18 mm. 

 The pars recurrens had a length, inclusive of the fused portion, of 8*2 

 cm., and extended forward to the level of the anus. 



At its anterior extremity the left ovary measured 10 ram. in width. 

 Its breadth increased very rapidly, and at a distance of 14 mm. from the 

 anterior extremity of the ovary, was 27 mm. ; at a point 6 cm. further 

 back the width was 30 mm. The ovary then diminished in breadth, 

 until at the level of the anus its width was reduced to 18 mm. The 

 caudal portion, at its posterior extremity, was 5 mm. wide. The pars 

 recurrens, at the point of fusion with the caudal portion of the ovary, 

 had a width of 9 mm., and at its anterior extremity a width of 5 mm. 



' The portions of the right and left ovaries, which extend into the caudal 

 ' region, do not unite, as some have asserted, but both are, towards the end, 

 1 enclosed in a peritoneal membrane, and are separated from each other by the 

 1 union of the membranes ; they have each on their inner face an accessory 

 ' ovary (pars recurrens ovarii). In rare cases is such an accessory ovary want- 

 ' ing either on the right or on the left side.' * The eggs are borne'pn the outer 

 surface of the ovary. ' The inner surface, that which is next the alimentary 

 ' canal, is smooth; it is covered in with an endothelium and presents no trace 

 * of germinative epithelium. This surface has received the name of the 

 1 vascular surface. The external surface is covered with lamellae, which 

 ' have on their surface sexual epithelium, and enclose ovules in their thick- 

 1 ness. This is the germinative surface. Brock is of the opinion that the 

 ' ovary of the eel is a primitive type.' f In the accessory ovary, the eggs are, 

 on the contrary, borne on the inner surface, its outer surface being in 

 contact with the inner surface of the caudal portion of the ovary. The 



* ' Lecture on the Organs of Reproduction, and the Fecundation of Fishes, 

 and especially of Eels/ by Dr Syrski.— Report U.S. Fish. Comm., 1873-4, 1874-5, 

 Wash. 1876. 



t Jules Macleod, 'Appareil Reproducteur femelle des Teleosteens,' Archives de 

 Biologic, Van Beueden, &c, vol. ii. f 1881. 



