690 DE. H. CHAELTON BA8TIAN ON THE ANATOMY AND PHT8I0L0GT 



probability, in the genus Spiroptera, although the vessels are most likely minute and diffi- 

 cult of detection. I found this belief upon the following evidence, Ebebth has carefully 

 examined three species of the genus, and makes no mention of the existence of ventral 

 glands in either, though he has described and figured* a delicate axial vessel in the lateral 

 band of Spiroptera uncinata. He discovered the lateral cervical pores in these animals, 

 and as he looks upon them in the Nematoids generally as lateral openings of the vessels, 

 taking the place of the single ventral pore, he probably never carefully searched for 

 this. ScHNEiDEEf, however, does state that the ventral opening exists in Spiroptera 

 obtusa, and I have been led to a similar belief from what I have observed in the same 

 animal. The specimens I examined had been preserved for a long time in spirit, and 

 were in a rather poor condition, so that I was quite unable to detect any vessels in the 

 lateral bands. Although I believe they exist, in all probability they are of small size if. 

 At all events I could not positively make them out, though I did detect a union of the 

 lateral bands beneath the oesophagus (Plate XXVI. fig. 20) close behind the head. Thus 

 a ventral opening was seen by Schneidek, an internal arch by myself, and a contained 

 axial vessel in another species of the same genus by Eberth. Spiroptera obtusa is most 

 remarkable for the great inequality in the size of its lateral bands; in the cervical 

 region of the body they are almost equal on the two sides, but throughout the greater 

 part of the extent of the animal the right is enormously developed (Plate XXVI. fig. 19), 

 forming a great projection, which near its middle occupies nearly one-third of the 

 general cavity of the body. A considerable quantity of fibrous tissue seems to enter 

 into its composition, and both it and the small one of the opposite side seem bisected 

 by an imperfect horizontal septum of this kind. 



I have carefully examined many specimens of ProsfJiecosacter infieanis, and in none 

 could I discover any trace of a ventral gland. At the anterior extremity, however, 

 close behind the mouth, I detected a distinct funnel-shaped depression, this being the 

 outer termination of a channel through the integument in the ventral region, at a level 

 very slightly posterior to that of the capillary lateral pores (Plate XXVII. fig. 3). From 

 the lateral bands, also, delicate processes were given off on each side, which met at the 

 ventral aperture, but neither in these, nor in the lateral bands § themselves have I 

 detected any actual vessel. If it exists, as the structures would seem to point out, it is 

 probably very small. 



I have now to describe some remarkable modifications in the arrangement of these 

 vascular or excretory canals which are met with in the so-called Filaria piscium, and in two 

 animals at present included in the genus Ascaris, viz. A. osculata and A. spiculigera. In 



* TJntersuch. uber Nemat. Taf. ix. 6. t MSllee's Archiv, 1858. 



t I have since ascertained that Schneider does report the existence of such delicate vessels communicating 

 with one another anteriorly ( Vide Ebehth, Untersuch. iiber Nemat. p. 64). 



§ It is very difficult to detect a delicate vessel in these bodies, either in their longitudinal direction, when 

 the lateral bands are solid and opaque as in this animal, or even more so in transverse sections ; a delicate- 

 walled vessel becomes obliterated by the mere mechanical process of making the section. 



