296 NATUEAL HISTOEY SOCIETY OF DUBLIN. 



outer layer, but they do not seem to be regular in their position or ar- 

 rangement. Towards the tail a considerable number of distinct oblique 

 lines are occasionally seen, radiating from the anus to the dorsal aspect, 

 but they do not seem to be deeper than the superficial tegumentary 

 layer. They commence at the ventral line, and extend symmetrically 

 on either side of it towards the dorsal surface, but stop short of the 

 middle of that aspect. Two lateral lines (Fig. 2, c) can be traced with 

 great facility, commencing narrow at the head, widening slightly in the 

 centre, and passing backwards to the posterior extremity, or tail, 

 where they also taper a little, and end near its tip by gradually dimi- 

 nishing ; but whether these lines be muscular — as Rudolphi thought — in 

 other species of Ascaris, or vascular — as supposed by Eberth — or nervous, 

 as imagined by Cuvier, Willis, and Cobbold, I could not even conjecture 

 in such a minute species ; they appear to me, however, to be most pro- 

 bably extensions of the integument inward, or lateral involutions pro- 

 longed into the thin subjacent longitudinal muscular lamina. These 

 lines appear to be made up of longitudinal striae, with dark granules in 

 their intervals. Anterior and posterior lines are also visible, but less dis- 

 tinct in general than the lateral. The tail is very variable in shape ; in 

 the female it sometimes is short, and rapidly acuminated ; in other speci- 

 mens it is long, attenuated, and occasionally even uncinated at its extre- 

 mity ; near the tip small papillary elevations are obvious, and in some 

 individuals give an obscure appearance of serration to its margin 

 (Plate III., Figs. 2, 4, 5). The tail of the male is much shorter, blunter, 

 and more rapidly narrowed to its rounded end, which is more bevelled 

 on its ventral than on its dorsal aspect, to accommodate the masculine 

 organs of reproduction. 



The head presents three tubercles, which are nearly equal in size ; 

 but these are not so distinct as they appear to be in other allied species ; 

 they exhibit several small irregular granulations on their inner or oral 

 aspect. On using gentle compression, I was able in several individuals 

 to see a fine, slightly curved tube projecting between the three tuber- 

 cles (Fig. 2, a) ; this, I think, is similar to the tube referred to by Bremser 

 in other species of Ascaris, which he takes to be the true mouth, but 

 which appearance "Wedl considers to be due to the protrusion of the 

 everted lining of the cleft proboscis. Through it I was enabled to 

 evacuate, by gentle pressure, currents of granules from the oesophagus. 



In a few of my specimens two lateral alas exist — one on either side of 

 the head ; but this appearance seems rather uncommon, as I could only 

 find it in about eight per cent, of the examined specimens (Fig. 3). "When 

 present, these wings commenced immediately outside the tubercles by a 

 raised or prominent circular collar, behind which the flat, slightly 

 wrinkled alas start, and extend backwards and outwards for a short 

 distance, when they rather suddenly contract until their margins be- 

 come continuous with the wrinkled integument. Though this appears 

 the usual disposition of the wings, it is sometimes departed from, as in 



