Dr. J. Blake read the following:
On the Organs of Copulation in the Male of the Embiotocoid 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 fœtus of the embiotocoid 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 impregnation, 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 maintained 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 appendages are of two kinds. In Embiotoca, Damolichthys 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 copulation. 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 commences at a short distance from the ventral attachment of the fin, a well marked groove is formed at the base of the fin, which affords an additional hold for the ventral fin of the female. After the season of copulation is over, and the testicles regain their quiescent state, this epithelium almost disappears. At the same time the mammary sack diminishes very much in size, so that when the testicles are reduced to their smallest size, hardly a trace of the sack remains. One or the other of these forms of appendages have been found on the anal fin of the male in all the species of embiotocoid fishes I have examined.
Mr. Stearns exhibited some fossils collected by Mr. Schmidt near Orleans Bar, Klamath County.
Professor Whitney exhibited some peculiar ores from Nevada and Mexico. Those from Nevada were antimoniate of lead, containing considerable silver. This occurs in Humboldt County, and in sufficiently large quantities to be mined and smelted, with success as is stated, the value of the silver being about $100 per ton. The Mexican ore is a pure oxide of antimony, which will be more fully described hereafter. It occurs in several mines in the northern provinces.
Professor Whitney made some remarks on the mineral species occurring in California and on the Pacific Coast of America in general. The following is an abstract of these remarks:
He stated that the number of minerals occurring in California, and on the Pacific coast in general, taking the country from Northern Mexico to British Columbia, was quite small in proportion to the area of the region. Especially among the silicates is there a great deficiency in species, and very few of those which do occur are found of sufficiently well crystallized form to be valuable as cabinet specimens.
The total number of species (following the fourth edition of Dana’s Mineralogy for names, etc.) believed to exist on the Pacific coast, including Northern Mexico, Arizona, California, Nevada and Oregon, is one hundred and ten, of which, however, thirteen are somewhat doubtful. Of the one hundred and ten, there are eighty-nine which occur in California. Some of the mineral species most common in other parts of the world, and especially in mining regions, are either entirely unknown here, or else exceedingly rare. Thus barytes, which is so abundant a veinstone in England and Germany, is almost unknown in the Sierra Nevada, having been only found in one or two localities, and there in small quantity. Fluor is entirely wanting in the Sierra Nevada, although found in some quantity in Arizona and Nevada. Not a trace of this elsewhere so common mineral has been found, so far as known, in California.
Among the silicates most universally diffused, but which are up to this time entirely unknown in California, the following may be mentioned as some of the most prominent: beryl, topaz, zircon, Wollastonite, scapolite, spodumene, Allanite, iolite, staurotide, kyanite, spinel, nepheline, datholite and all the zeolites, in other countries so abundant where volcanic rocks occur. Not a well defined specimen of a zeolite has yet been found within the borders of California.