XXI INTEGUMENT—REPRODUCTIVE ORGANS 519 
many little cavities, some of them conical and tapering to a 
minute external pore, the others more regularly tubular. Some- 
times, but according to Hoek rarely, the tubular pore-canals 
communicate with, or arise from, the conical cavities. The pore- 
canals transmit a nerve for the supply of sensory hairs, often 
forked, which arise from the orifice of the canal in little groups 
of two or more, sometimes in rosettes of eight or nine. These 
setae are small or rudimentary in <Ascorhynchus and_ totally 
wanting in Colossendeis; they appear to be extremely large 
and stellate in Paranymphon. The conical cavities contain 
proliferated epithelial cells, blood-corpuscles, and cells of more 
doubtful nature that are perhaps glandular. According to Dohrn, 
glands exist in connection with both kinds of integumentary 
perforations, and he suspects that they secrete a poisonous fluid 
in response to stimuli affecting the sensory hairs; Hoek, on the 
other hand, is inclined to ascribe a respiratory function to the 
cavities; but indeed, as yet, we must confess that their use is 
undetermined. 
Reproductive Organs.—In each sex the generative organs 
consist of a pair of ovaries or testes lying above the gut on 
either side of the heart; in the adult they are fused together 
posteriorly at the base of the abdomen, and send long diverticula 
into the ambulatory legs. In the female Phoxichilidium, at 
least, as Loman has lately shown, the fusion is complete, and the 
ovary forms a thin broad plate, spreading through the body and 
giving off its lateral diverticula. The diverticula of the testes 
reach to the third joint of the legs, those of the ovaries to the 
fourth, or sometimes farther. The ova ripen within the lateral 
diverticula, chiefly, and sometimes (Pallene) exclusively, in the 
femora or fourth joints of the legs,’ which, in many forms, are 
greatly swollen to accommodate them; the spermatozoa, on the 
other hand, are said to develop both within the legs and within 
the thoracic portions of the testis. The genital diverticula may 
end blindly within the leg, or communicate through a duct with 
the exterior by a valvular aperture placed on the second coxal 
joint. Such apertures occur, as a rule, on all the legs in the 
females, in Rhynchothoraz and Pycnogonum on the last only. In 
the males an aperture is present on all the legs in Decolopoda and 
Phoxichilidium ; on the last three in Nymphon and Phoxichilus ; 
1 In the second joint in Ascorhynchus abyssi, Sars, and A. tridens, Meinert. 
