20 
The authors have proved (1889) that in Aspidoccia the male is hinged by a thread 
which proceeds from a hole on the ventral side of the front part of the head: »ce filament 
est secrété par deux grosses glandes cémentaires probablement homologues de celles qui 
servent a la fixation chez les Cirripédes«. No doubt it is this comparison on which they 
base their opinion that the genital aperture is found on the head, and also that the spermatic 
glands secrete the viscous substance which forms the thread, as these organs are believed 
to perform this double function in the Cirripeds). A slight basis indeed for such remarkable 
statements! The observation about the hingement of the male is correct, but then, has the 
thread to disappear in order to allow the spermatophores to come out of the hole, or is the 
order of the two processes to be inverted, or does the male possess another genital aperture 
on its front near the base of the thread? Unfortunately we get no answer to all these 
legitimate questions — though indeed we can scarcely imagine any possibility besides these 
three. No, the doctrines about the genital aperture on the head and the double function of 
the sexual organs in the Choniostomatide are postulates without any foundation. Within 
the family mentioned it is an ordinary phenomenon to find the male attached by a thread; 
this prevents it from being washed away and allows it to creep as far as the thread can 
reach, giving it frequent opportunities to fix its spermatophores on the entrances to the 
receptacula seminis. Besides, the genital aperture is not found on the head; in Spheronella 
paradoxa I have been able to prove the existence of two genital apertures at a short 
distance from each other on the ventral side of the trunk: from each spermatotheca proceeds 
an efferent duct forward and obliquely towards the median line, and these canals open on 
the posterior side of the depression between the first pair of trunk-legs, or at least somewhat 
behind the basis of the maxillipeds. But then, what remains of the hypotheses advanced as 
facts by the two authors, that the genital aperture of the male in the Choniostomatid is found on 
the head, and that the »canaux génitaux« secrete the viscous substance by which the animal 
attaches itself? Nothing, absolutely nothing! And what remains of their best proof -— based 
on these organs —, that Choniostomatide and Herpyllobiide ought to be grouped in one 
family? Equally: nothing! except a rather surprising impression of the loose method of the 
authors: to establish unreliable conjectures as facts in order to prove an absurdity. 
Though I suppose that most readers have now formed a pretty clear idea of the 
great differences between the two families, I will give a summary. The likeness between 
the two families is limited to the following features: both are parasitic Copepoda, in which 
the males are several or many times smaller than the females; in both sexes the body is 
small, sub-globular or oblong; the last larval stage of Herpyllobiide is the first Cyclops 
stage, it resembles to a certain degree the larva just coming out of the egg in the Cho- 
1) | will not here enter upon criticisms which have appeared elsewhere about Darwin’s unfortunate 
statements upon this subject, nor on Giard’s later suggestions concerning Rhizocephala. 
