194 Miscellaneous. 



tion which is as rare amongst insects as it is common in the Crus- 

 tacea, the male Ephemeridoe are provided with two copulatory 

 organs *. 



These organs arc attached to the penultimate inferior half-segment 

 of the abdomen. They are of horny consistency, of a curved form, 

 hollow within, and pierced at their free extremity with an orifice 

 through which the seminal fluid escapes during fecundation. They 

 are situated'at some distance Avithin the two corneous, curved, and 

 quadriarticulate pieces which form the force/js, or copulatory armature 

 by which the male holds the female during copulation, and which, 

 from the point of view of philosophical anatomy, is nothing but an 

 abdominal foot converted into an organ of prehension. 



The author of the ' Biblia Xaturje ' has represented the testes of 

 Palinrjenia longlcaiula in the form of two elongated tubes with the 

 surface uneven, as if mamillated. He adds that at their posterior 

 part they are furnished with two smaller sacs, which he believes to 

 be seminal vesicles ; but he dees not mention either the deferent ducts 

 or the ejaculatory canals. Now these ducts and canals exist, as we 

 have ascertained by dissecting several individuals of P. longicauda, 

 obtained direct from Holland, but presei*ved for some time in alcohol. 

 A maceration of two or three hours in slightly tepid water has en- 

 abled us to isolate the testes of thisEphemerid without much difficulty, 

 and thus to make sure that their structure is identical with that of 

 the testes of Baeti.s. 



"We have sought in vain for the supposed seminal vesicles described 

 by Swammcrdam. Leon Dufour states that he could not find the 

 least trace of them in Epliemera nigrimana. We are therefore led 

 to believe that the celebrated Dutch naturalist mistook for seminal 

 vesicles simple adipose sacs like those which we have ourselves ob- 

 served in Baetis sulphurea, and which, at the first glance, have some 

 little resemblance to seminal vesicles. 



However this may be, our dissections, repeated several times, enable 

 us to affirm that no seminal vesicles exist in the Ephemeridae that 

 we have studied. As to the testes, they have struck us by their 

 comparatively considerable size, and especially by their resemblance 

 in form and their analogy of structure to those of the Li- 

 bellulinae, and even to those of the higher Yertebrata in this 

 respect, that, like ' the latter, they are found in final analysis 

 to consist of a tube containing spermatic capsules {oeiifs males, C. 

 Robin) lodging smaller cells (cellules emhryonnaires males, C. Robin), 

 in the interior of which the si)ermatozoid8 are developed. 



Female Genital Apjparatus. — In several thousands of individuals 



• In assuming the existence of two penises in the Ephemerae we shall, 

 perhaps, seem to some entomologists to he committing a serious mistake, 

 and to be taking for penises the pieces (which are often absent) to which 

 L^on Dufour has given the name of '' volselles," and which, according to 

 him, are constituent parts of the copulatory armature. But he.sides that 

 these " volselles " are often deficient in insects, we have, to support the 

 correctness of our determination, the indisputable fact of the excretory 

 seminal duct passing through these organs which we regard as two penises. 



