92 W. BLAXLAND BENHAM. 



ible, and may be regarded as fluid ; for on the contraction 

 of the wall of the reservoir it is driven forwards so as to 

 distend the acanthophore, pushing forwards the radial muscle 

 and the membranous anteinor wall of the acanthophore. 



Turning now to the receptaculum rostelli, it has similarly a 

 wall of two layers of muscles, complete posteriorly, but 

 reflected distally (anteriorly), so as to be continuous with the 

 wall of the rostellum at the neck. 



The contents of the receptacle in D. mi nut a is of two 

 kinds. In the distal region is a very faintly granular fluid 

 (not taking the stains) with scattered nuclei, without evident 

 arrangement or cell boundaries (fig. 19, _p). But the bottom 

 of the receptaculum is occupied by a very deeply staining 

 granular mass, so deeply staining in boracic carmine as to 

 hide the nuclei which are scattered therein ; but in haema- 

 toxylin the nuclei stain more deeply. This mass is contained 

 in four elongated sacs (tigs. 16 — 22, s), the membranous walls 

 of which meet below the bottom of the rostellum, so as to 

 form an X-shaped septum in transverse section, and a longi- 

 tudinal one when seen in longitudinal section (as noted by 

 V. Linstow in 1890). These granule sacs fill the post-rostellar 

 region of the receptaculum, and push forwards about halfway 

 along the latter, where they end by obliquely tapering off, so 

 that the less granular material distally intervenes between 

 them and rostellum (figs. 1, 9). The receptaculum is moved 

 by extrinsic muscles, some of which pass upwards and out- 

 wards from the wall, near its anterior end, diverging in a 

 fan-like manner, to be inserted in the apex of the scolex 

 above the suckers (fig. 16, m^). 



These muscles seem to be in four groups or bundles, two 

 on each side of the receptaculum, lying between it and the 

 chief nerves issuing from the brain. Other muscles pass 

 downwards and are lost behind the suckers (m). But it does 

 not seem that these extrinsic muscles play any great part in 

 the protrusion of the actual I'ostellum. In this process we 

 have to distinguish two independent movements ; firstly, the 

 protrusion of the rostellum ; and secondly, the distension or 



