94 



s. GOTO. 



on its external, concave face bears a number of recurved, chitinous 

 spines, whicb togetlier constitute the chitinous penis. Each of tliese 

 hooks consists of a mound-shaped basal ])ortion and a h(jl]ow, spinous 

 distal portion. The substance of the penis bull)s has the same his- 

 tological structure as that in Diclidopliora. 



Calicotylc — In this g-enus the connective-tissue penis is a some- 

 Avhat kidney-shaped body formed of fibrous tissue containing nuclei, 

 separated however, from the surrounding mesenchyma. by a distinct 

 membrane, except at one {)lace where the fibres of the surrounding 

 niesenchvnia are seen to l)e directly continuous witli those of the penis 

 (IM. XTX, fig. 11). The ])enis has one end smaller than the other, 

 and in its natural state, is placed so that its smaller end occupies 

 a more dorsal position in tlie body than the other (PI. XIX, figs. 7 

 & 11). Its smaller end is directly continued into the chitinous penis, 

 which is an exceedingly long, hollow tube with obliquely cut end, 

 and is twice l)ent on itself in sucli a way that the middle portion 

 crosses the middle of the distal portion (PI. XIX, fig. 10). As 

 just side, its base is directly applied to the outer end of the con- 

 nective-tissue penis (PI. XIX, fig. 11); and it lies in a tubular 

 ca>ity just large enough to receive it, the direct continuation of the 



oonital atnum. 



Moiiocotylc — The connective-tissue penis is in tliis genus a 

 somewhat pear-sliaped organ attached to the body by its smaller end 

 at the l)otiom of the genital atrium (PI. XVIII, fig. o), and is perfo- 

 rated by a canal. The substance of tlie penis consists of fibres which 

 are of similar general appearance to those of the suckers of Micro- 

 cot i/Ic and some other genera, but are finer and stain better with 

 hiematoxylin. They are arranged perpendicularly to the surface of 

 the penis, and at its base are seen to be directly continued into the 

 mesenchyma of the body, which, however, consists in this region of a 



