564 DR. H. CHARLTON BA8TIAN ON THE ANATOMY AND PHYSIOLOGY 



anus, and are of an elongated pyriform shape ; whilst in other species, as may be well 

 seen in Oncholaimus vulgaris and in the Leptosomata, they are still more elongated and 

 tubular in form, and extend for some distance into the cavity of the body by the side of 

 the intestine. These appendages only exist in species ha\'ing otherwise large and well- 

 developed suckers, and their main function seems to me most likely to be connected 

 with the more efficient action of these structures. According to the views of Leydio 

 and Eberth *, these sacs are " tail-glands " (Schwanzdriise) opening by a terminal 

 " papilla " and secreting a clear gummy substance, which enables them to adhere to 

 sun-ounding objects. I do not think this mechanism of adhesion a very probable one ; 

 and although in a specimen of Oncholaimus vulgaris I have seen expelled from these 

 bodies through the terminal orifice, at irregular interA'als, small quantities of fluid 

 rendered apparent by the minute molecules suspended in it, still their generally clear 

 appearance, and the absence of all the main characters belonging to glandular structures 

 in other parts of the body, lead me rather to discountenance this view of their nature. 

 Instead of " glands " I would term them sucker-tubes, believing them to be contractile 

 in their nature and mainly destined to perfect the action of the sucker, which seems to 

 operate by the ordinary principles of hydrostatic pressure, rather than by the adhesive 

 properties of gummy secretions. 



Integiimental pores. — In Dorylaimits stagnalis I first detected a number of minute 

 channels through the integument, and though I have since recognized these in many 

 other free Nematoids (especially in the larger marine species), in no animal can they 

 be so well observed as that in which they were first discovered. The thickness of 

 the integument, and the number of the pores in the lateral regions of the body of this 

 animal, are the reasons which make it so suitable for examination. They seem to be 

 very numerous over those portions of the lateral regions of the body, from end to end, cor- 

 responding in position with the internal lateral bands. Those, however, situated towards 

 the posterior extremity of the body are most favourable for examination, owing to their 

 increased number, size, and distinctness in this situation (Plate XXVIII. figs. 3 & 4). 

 Extending through the chitinous portion of the integument they are about -awo" long, 

 capillary in breadth, commencing internally opposite a conical projection of the true 

 skin, and terminating at the external surface in a minute depression. That these are 

 channels through the integument I have not the slightest doubt. I have detected 

 similar pores in another freshwater species {Tripyla glomerans) having an imusually 

 thick integument ; in this also the pores were in the lateral regions of the body, though 

 they did not exist in nearly so great abundance as in Borylairmis stagnalis. Amongst 

 the marine species I have recognized similar integumental channels most plainly in 

 Leptosomatum gracile, L. figuratum (Plate XXVIII. fig. 33), and in Phanodenna Cocksi 

 n the lateral cervical regions, though also less distinctly in the lateral region throughout 

 the body. In addition they occur along the mid-dorsal and ventral lines of the Lepto- 

 somata. In Oncholaimus vulgaris they also exist in the mid-ventral and dorsal regions, 



* Untersuch. iiber Nemat. 1863, p. 8. 



