ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 459 



to lead to the oesophageal nervous ring of the round- worms, by 

 imagining a gradual approximation of the two ventral cords, until at 

 last they unite to form a single ventral trunk ; the single dorsal cord 

 may be supposed to have arisen by a similar fusion of the two dorsal 

 nerves. Attention is directed to the important observation made by 

 Joseph that in young Ascarids there is a distinctly paired ventral 

 cord, and that between the cords there are transverse anastomoses, 

 which may be compared with those found in Platyhelminths. 



The lateral nerves appear to be represented by remnants only, and 

 these, which are only evident in the anterior region of the body, pass 

 into the ventral cord. 



Although Biitschli thinks that he has been able to bring together 

 evidence as to the general relations which obtain between the nervous 

 system of certain Platyhelminths and that of the Nematohelminths, 

 he wishes it to be distinctly understood that he does not look upon 

 the present flat- worms as being the ancestors of the round-worms, nor 

 does he depart from the phylogenetic views which he expressed nine 

 years ago. 



Host of the Larva of Echinorhyncus clavseceps.* — This has 

 been found by M. A, Villot in the aquatic larva of Sialis niger. The 

 young EchinorJiyncus lies in a transparent cyst in the fat-body of 

 the insect. It is sub- cylindrical in shape, about 0'56 mm. long, and 

 differs from the adult form only in encystment, size, transparence, and 

 sexual immaturity. There are eighteen hooks on the proboscis, 

 similar to those of the adult, and they are set upon the wall of 

 invagination of the proboscis in three reversed series. 



As regards the lemnisci, Villot combats the theory of Megnin 

 that these organs represent the two intestinal tubes of Distomidas. 

 " If anything represents a digestive apparatus in the Echinorhyncus 

 (larval or adult), it can only be the narrow canal which communicates 

 with the exterior by the terminal orifice of the proboscis, traverses 

 the receptacle and cephalic ganglion, and finally passes into the body- 

 cavity to form the suspensory ligament of the genital organs." 



Villot identifies this larva with that figured in 1871 by Ch. Eobin 

 as a Nematode parasite of Nephelis. 



Nervous System of Taeniae. f — The researches of M. J. Niemiec 

 were made on the four following species of Tcenia, viz. Coeniirus, 

 elliptica, serrata, and mediocanellata. 



The following differences were noted between T, coenunis and 

 sirrata: — 



1. Filaments, very distinct in the upper part of the scolex, are 

 given off from the nervous ring of T. serrata, which, after ramifying, 

 are lost in the muscles of the booklets. 



2. The eight descending branches of the nervous ring have 

 distinct points of departure, while in T. coenurus they are united in 

 pairs at their point of origin. 



3. There are no filaments which, issuing from the ring, go directly 

 to the sucker. 



* Zool. Anzeig., viii. (1885) pp. 19-22. 



t Arch. Sci. Phys. et Nat., xiii. (1883) pp. 249-5.3. 



