( aere9 
IV.—On the Extrusion of the Seminal Products in Limpets. 
By W. H. Datz, Smithsonian Institution, U.S.A. 
In a paper published in the American Journal of Conchology, 
Part 3, 1871, I brought together a summary of the various 
details published from time to time by various naturalists, upon the 
anatomy and physiology of this group. In that paper it was 
shown that the manner in which the seminal products were freed 
from the ovary and testis, and the passage by which they reached 
the exterior, were unknown, and from the investigations of 
Lankester and myself, that the existence of the oviduct figured 
by Cuvier,* if not actually disproved, was at least a matter 
of grave doubt, and had not been confirmed by any subsequent 
examination. Lankestert had suggested that the passage of 
the ova to the exterior was made through two orifices first de- 
scribed by him and termed “capitopedal orifices.” These were 
said to open, “one on each side of the head in the angle formed 
by its junction with the muscular foot, and (internally) opening 
into the blood sinus surrounding the pharyngeal viscera. He 
also described an opening communicating between the “ peri- 
cardium and the supra-anal articulated sac,’ or accessory renal 
organ. The latter I have never been able to demonstrate to my 
own satisfaction, but I do not assume to dispute its possible exist- 
ence. Instead of opening externally in the angle formed by the 
head and the foot, the “capitopedal orifices,” if I have correctly 
identified them, are situated on the back of the neck, so to speak, 
or more properly on the transverse portion of the integument above 
the head and in front of the main pericardial chamber in the angle 
formed by the neck and the inferior surface of the mantle over the 
head. Mr. Lankester found them in Patella vulgata, but I have 
never been able to detect them in the few alcoholic specimens of 
that species which I have been able toexamine. In fresh specimens 
of Acmexa patina and testudinalis, I have generally been able to 
find them, and in the living animal they are of an orange colour. 
In Ancistromesus Mezxicanus they are quite prominent in some 
cases and almost imperceptible in others. They also differ in 
character. In Ancistromesus (one of the Patellide), they appear as 
true orifices, in the acmaas they present the appearance of an 
elongate, narrow, glandular mass, from which, internally, a duct 
is not always traceable. In some individuals they appear entirely 
absent or abortive. My own opinion of their function is, that they 
are aquiferous pores, such as are common to many mollusks, 
through which water passes into the circulation directly in the 
* “Mem. sur Jes Moll.’ 15, 1817. + ‘Ann. Mag. N. H.’ xx, p. 334, 1867. 
