622 PROFESSOR E. RAY LANKESTER. 
it has been suggested, with much plausibility, that the 
pectens (the lamelliferous appendages of the eighth segment) 
serve as tactile organs, guiding and stimulating the move- 
ments which result in the coitus. 
The female Scorpion is even further specialised in 
reference to its genitalia as compared with Limulus. Whilst 
it retains the reticulate gland and the ¢wo ducts, each with 
its external aperture as in Limulus, it develops no special 
spermatheca or receptacle for the spermatozoa received in 
copulation, but the semen passes along the tubular oviduct 
and into its net-like branches. Here the semen fertilises the 
ova, which are placed in follicles set upon the sides of the 
mesh-forming ovarian tube. The development of the egg pro- 
ceeds actually within the follicle and the Scorpion produces 
her young in the living condition. 
Connected with this viviparous character is the specialisa- 
tion of the egg-bearing follicles carried by the ovarian mesh- 
work. In Limulus more numerous eggs are produced, and 
there is no specialisation of follicles, but from all parts of 
the ovarian reticulum egg-cells appear to develop and to 
become free in the lumen of the tubular structure of which 
the reticulum consists. 
The best account extant of the generative organs of the 
Scorpions appears to be that of Dufour (loc. cit.), who 
studied fresh specimens, but his account leaves everything to 
be done in respect of the histology, and one may even hesi- 
tate to feel confidence in his description of large features. 
There is, also, no complete account of the generative 
glands of Limulus. We may hope that the American 
naturalists, who have abundant Limuli on the sea-shore, will 
soon give us a precise account of the form of the fully 
developed ovary and testis, as well as an account of their 
histology. At present our knowledge is confined to the 
figure given by Owen of a portion only of the ovary, and to 
his description, which is very definite as far as it goes, and 
sufficient for the purpose of a general comparison with 
Scorpio. The testis was immature in a male specimen 
recently dissected by me, and in an earlier dissection I was 
unable to clear out this organ fully on account of the special 
objects which I had in view. 
I was, however, able on that occasion to determine an 
important point of agreement between Limulus and Scorpio, 
namely, in regard to the character of the spermatozoa. Itisa 
familiarfact thatthe spermatozoa of the Arthropoda exhibit the 
greatest diversity of form, and also great want of uniformity, 
as to the presence or absence of a motile flagelliform ‘tail. 
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