Muscles of the slieafli of Penis. Lubncatinf/ Glands 63 



In Nemastomatoid«, at any rate in JV. argenteo-limulatum (PI. VI., fig. 22, mp), they 

 rise from the dorsal side of the sheath along the greater anterior portion — not from the 

 hindmost portion — of that part which i.s situated above the thick part of penis containing 

 its muscles, and also from that part of the sheath situated above the posterior portion of 

 the slender part of the penis. The third pair of muscles (PI. VI., fig. 22, me) are inserted 

 on the sheath close to its anterior extremity, and pass from thence backwai-ds, diverging 

 a little, and attach themselves to the dermoskeleton. In our opinion they serve to keep 

 operculum genitale closed. Ischyropsalidoidte and Nemastomatoidse possess besides a fourth 

 set of muscles (PI. VI., figs. 18 and 22) on the posterior part of the sheath, but their 

 course is not the same in the two families. lu Ischyropsalis this pair of mu.scles (fig. 

 18, mf) commence posteriorly on the dorsal side of the sheath, where they meet in the 

 middle line, and pass from thence forwards and downwards, so that they reach much 

 farther forwards on the ventral side than on the dorsal side. In Nemastoma, on the 

 contrarj', they commence on the posterior part of tiie ventral side of the sheath (PI. VI., 

 fig. 23, mg) and pass forwards and upwards {mg on fig. 22), ending anteriorly a little away 

 from the middle line near the insertion of m. pi'otrac tores. In Nemastoma, finally, a fifth 

 pair of muscles are found (PI. VI., fig. 22, mh), of which the anterior extremity is fixed to 

 the sheath immediatel}- in front of the last-mentioned pair of muscles, from which point 

 they pass backwards and a little outwards to the skin. We have therefore no doubt but 

 that this pair of muscles serve to expand the sheath when penis is to be exserted, a view 

 which is confirmed by the fact that this pair of muscles are found only in Nemastoma, 

 that is to say in the only genus where penis is rather abruptly divided into two parts 

 of different thickness, and by the circumstance that they are attached to the sheath precisely 

 at the junction of the thicker and the more slender part of penis, as may be seen by 

 comparing fig. 23 (on PL VI.) with fig. 22. 



In Cyphophthalmi the muscular equipment of penis and its sheath is but little developed. 

 Penis is furnished only with m. retractores (PI. I., fig. 1 v, mr) and the sheath possesses 

 only one pair of muscles (md), which pass obliquely outwards from its anterior portion to 

 the integ-ument. It cannot be doubted that thev are intended to dilate the sheath, when 

 penis is to be exserted, and it is worth noticing that these muscles occur precisely in this 

 group, where penis is short and blunt. At the time when we examined penis in those 

 few specimens of Cyphophthalmi which could be spared for the purpose of dissection we 

 were not aware that the arrangement of these muscles offers interesting .systematic characters ; 

 but we nevertheless believe ourselves justified in saying that no other muscles are found 

 here than those we have mentioned. 



Large accessory glands opening in the anterior portion of the sheaths of both penis 

 and ovipositor have long ago been noted in Phalangioidte. In our opinion their secretion 

 serves to facilitate the sliding of these organs foi'ward and backward, for which reason 

 Sorensen (6) has called them lubricating glands. The last-named writer found them in 

 PacJnjloides uncinattis of the family Gonyleptoida?, but of a different shape from those in 

 Phalangioidse. From this he concluded that the differences in respect of these glands wei'e 

 of systematic value for the characters of the sub-orders ; but that is not the ca.se'. Of 



' In Pachijloides uncinatiis Sorensen (6, p. 195, PI. II., muscular stratum; in a male of the same species we have 

 fig. 27) found only one such gland, without lobes and small — however found a pinr of glands about twice as long as the 

 only half as long as the diameter of the sheath including its diameter of the sheath. In the male of Discocyrtus testu- 



