ACADEMY OF NATURAL SCIENCES. 371 



Donations to the Cabinet : Two packages of plants from France 

 and Australia, by Mr. Bolander ; these plants were collected by 

 Dr. F. Mtiller, Director of the Botanical Garden at Melbourne, 

 and by Rene Le Normand, of Vire, France, and sent to Mr. 

 Bolander in exchange for Californian plants. 



Dr. J. Blake read the following : 



On the Organs of Copulation in the Male of the Embiotoeoid 



Fishes. 



BY JAMES BLAKE, M.D., F.R.C.S. 



Some months since I presented a communication to the Academy pointing 

 out the manner in which the foetus of the embiotoeoid fishes was nourished 

 whilst it was being developed within the ovisac. (See p. 314.) I there stated 

 that the ingress of water into the ovisac would not take place at all freely, as 

 the organ communicated with the surface by a narrow canal surrounded by 

 muscular fibres. This structure of the oviduct would evidently oppose an 

 obstacle to the entrance of the semen into the ovisac for the purpose of impreg- 

 nation, unless some means exist by which the ventral surfaces of the fish can be 

 maintained in contact during the act of copulation, as the penis consists of a 

 slightly developed tubercle which cannot penetrate for any distance into the 

 oviduct. From the direction of the orifices of the penis and oviduct it is 

 evident that anything like a perfect contact of these organs can only be main- 

 tained whilst the fishes are in a reversed position, so that the head of one fish is 

 towards the tail of the other. In order that contact may be maintained whilst 

 in this position, we find the caudal fin of the male fish furnished with certain 

 appendages which enable it to give a firm hold to the ventral fins of the female, 

 so that close contact of the ventral surfaces can be maintained. These append- 

 ages are of two kinds. In Embioioca, Damolichtlujs and some other genera, 

 we find a well developed mammary elevation situated near the anterior part of 

 the anal fin on both sides, terminating in front by a teat-like process. In 

 Amphisticus, Holconotus and some other genera, this mammary appendage is 

 wanting ; but its place is supplied by a bony transverse plate with serrated 

 edges, inserted in the fin some distance farther back and parallel to the fin 

 rays. In addition to these plates there are also found cartilaginous ridges with 

 roughened borders, placed in front of the plates, and running parallel with the 

 edge of the fin. I think there can be no doubt but that these fin appendages 

 serve the purpose I have assigned to them, for on placing the fish in the 

 reversed position, with the orifice of the oviduct and penis in contact, it will be 

 seen that they enable the ventral fins of the female to secure a firm hold on the 

 anal fin of the male, so as to keep the fish in contact during the process of cop- 

 ulation. At the season of copulation, the anterior surface of the anal fin in 

 the male becomes covered with a thick layer of firm epithelium. As this com- 

 mences at a short distance from the ventral attachment of the fin, a well marked 



