176 CLASS V. 



Tcenia serrata, which in its developed state resides in the small 

 intestine of the dog, was found in all cases. The experiments were 

 performed so frequently, and with such precautions as to render the 

 results incontestable 1 . The cyst is a secretion of the infested animal, 

 and derives its blood-vessels from it. 



There is reason to conclude that a nervous system exists in 

 most Entozoa. In Bothriocephalus BLANCHAHD describes a small 

 ganglion on each side of the head (probably connected by a trans- 

 verse band) , which sends a fine thread forwards and backwards ; but 

 he was not able to detect the distribution of these 2 .] No nerves 

 have been discovered in the incomplete cystic forms. In Distomes, 

 and various other suctorial worms, two small ganglia have been 

 seen near the mouth, which are united by a transverse band that 

 runs over the oesophagus. From these two threads arise that have 

 a parallel course through the body, become finer backwards, and 

 give off some lateral branches 3 . In the thorn-headed worms there 

 is, according to the investigations of VON SIEBOLD, in different 

 species of Echinorhynchus, a nervous mass at the base of the pro- 

 boscis, from whence threads radiate in all directions, whose course 

 is not easy to follow. In Pentastoma a large nervous ganglion lies 

 beneath the oesophagus, from which a nervous ring arises that runs 

 transversely above the oesophagus; small branches go from the 

 ganglion to the muscles of the mouth and the surrounding parts, 

 and two threads proceed longitudinally, one on each side, back- 

 wards, giving off fine branches, and, at last, losing themselves in 

 the muscular tissue 4 . In Strongylus gigas the nervous system forms 

 a flattened ring round the commencement of the oesophagus, and a 

 string running backwards in the middle of the abdominal surface, 

 which ends in a ganglion close by the anus. From the string arise 

 at short and nearly equal distances transverse nervous threads. 

 Special organs of sense are not found in the intestinal worms, with 



1 See Band u. Blasen-w. s. 80 95. 



2 BLANCHARD Ann. des Sc. not. 30 Sdrie, Zool. Vol. xi. pp. 113, 114, CUVIEB 

 e"dit. illus. Zooph. pi. 26. fig. i d. 



3 MEHLIS Observat. anat. de Distomate; DIESING in Amphistoma giganteum, Wiener 

 Annalen I. p. 146, Tab. xxii. fig. 16, &c. 



4 OWEN Transact, of the Zool. Soc. i. pi. 41. fig. 13 ; TODD Cyclop. 1. 1. p. 130, 

 fig. 78 in Pentastoma tcenio'ides; DIESING Wiener Annal. i. Tab. n. figs. 7, 19, in 

 Pentast. prdboscideum. 



