Penis in Lnniatores and Cjiphophthalmi 61 



two principal parts (PI. VI., figs. 30 anrl 31, 33 and 34), a dorsal and a ventral one. The 

 former {d) of these, which contains the continuation of the seminal dnct, is rather soft 

 and the end of it is somewhat bent upwards, bearing on its extreme point the opening 

 of the seminal duct, which is generally very small, but proportionately large in Assamioidse 

 (fig. 34). On the ventral surface of this part processes occur of varying shape and number ; 

 in most cases there is, however, only one (fig. 31); in A-ssamioidse (that is in Maracaiidus) 

 there are none (fig. 34). The other principal part of glans is a ventral plate (e) variously 

 equipped with marginal spines, and which in most species is concave on the dorsal side, 

 so as to embrace to some extent the dorsal main part of glans ; in Assamioidas (figs. 33 

 and 34) the ventral portion embraces the dorsal one entirely, so that the lateral margins 

 of the former coalesce completely, without so much as a suture remaining to indicate the 

 fact of their having been originally separate. It is no doubt in accordance with this fact, 

 that the ventral plate is more distinctly separate from corpus penis in Assamioida? than 

 in most other cases ; generally the boundary between them is indicated only by a very 

 fine line (fig. 31). In most Laniatores the distal end of corpus is somewhat excavated so 

 as to embrace to some extent the dorsal part of glans, which is thus capable of a little 

 passive movement in all directions ; the same is the case with the whole of glans in 

 Maracandus. In a paper quite recently published Loman states (g) that corpus penis in 

 Trisenonychoida? contains a muscle subservient to the erection of glans. We have examined 

 the structure in Acumontia rostrata Pock, and found that Loman is right. We think that 

 our figures (PI. VI., figs. 3f) and 37) sufficiently plainly .show the shape of the organ ; we 

 may only add that the ventral plate (e) is deeply cleft in the middle line, a feature not 

 visible on our figures. 



In Cyphophthalmi the shape of penis is very different from that which we have described 

 as occurring in the two other stiborders, as may be seen on our figures (PI. I., figs. 1 os 

 and 1 //; PI. IV., figs. 1 o, I p and 1 g; PI. V., figs. 1 m, 1 n and 2 o). Whilst in the other 

 sub-orders this organ is elongate, slender and more or less firmly chitinized, it is in Cyph- 

 ophthalmi, on the contrary, short, thick and rather slightly chitinized, the chitine being fairly 

 thick only in the distal fourth or fifth part of its length. Nor can penis well be said 

 to con.sist of two clearly distinct parts in this group. It is true that the setae, which 

 are stout and very long, especially when compared with the length of the organ itself, are 

 all placed on its distal portion, and that on this ground it might be allowable to distinguish 

 between two principal parts of penis in this group also ; but we do not feel justified in 

 doing so. — The apical portion in PurcelUa (PI. IV.) and Siro (PI. V., fig. 1 m) shows some 

 thicker lines in the integument on the upper surface; in PurcelUa some similar ones are 

 seen also on the sides, as well as a transverse strip on the under surface. 



Our figures of penis in three out of the four genera which we have examined, Stylocellns 

 (PI. I., figs. 1 X and 1 y)\ PurcelUa (PL IV., figs. 1 o — 1 q) and Siro (PI. V., figs. 1 vi and 1 n), 

 are, we believe, sufficiently accurate to render detailed descriptions superfluous. The apical 

 extremity of penis is prolonged into a cone which protrudes a little on the ventral side 

 of the opening for the evacuation of semen. This cone is as a rule slightly flattened, but 

 in Stylocellns it is much depressed, the apex of it being rounded and emarginate. The 

 proximal portion of penis contains several bundles of muscular fibres, which mostly have 

 a longitudinal course. In PurcelUa and Stylocellus there are besides a couple of bundles 

 of fibres running in a plainly oblique direction. We regret having been unable to decide 



