50 



ON CLASSIFICATION. 



is difficult to see with what these can correspond if not with 

 some modification of the water-vascular system.* 



Fig. 23. 



Fig. 23. — The Echinorhynchus of the Flounder. — A. Diagram exhibiting the relative 

 position of the organs, a. Proboscis, 6. Its stem. c. Anterior enlargement, d. 

 Body. e. Posterior " funnel." /. Neck. g. Meniscus, h. Superior oblique tubu- 

 lar bands, k. Inferior muscles of the proboscis. /, m. Genitalia, o. Penis, or 

 vulva. B. Lower extremity of the stem of the proboscis, a. Ganglion, b. Inter- 

 space, d. Outer coat. c. Inner wall, e. Tubular band, with the nerve h. f. Mus- 

 cular bands, g. Suspensorium of the genitalia. C. Part of the female genitalia. 

 a. Ovary. 6 6. Ducts leading from ovary to uterus ( sperm id ucts ?). c. Open mouth 



of oviduct. 



d, e. 



Uterus and vagina. 



Leaving the division provisionally termed Scolecida in this 

 confessedly unsatisfactory state, I pass on to the Anxlltda, a 

 class of large extent, containing the leech, the earthworm, the 

 Sijmnculus, the lobworm, the seamouse and Polynoe (Fig. 24), 

 the Serjmla, and the Spirorbis. 



All the members of this class possess a nervous system, 

 which consists of a longitudinal series of ganglia, situated along 

 one side of the body, and is traversed anteriorly by the 

 oesophagus, the prse-cesophageal, or so-called " cerebral," ganglia 



* The recently published investigations of Leuckart, while they demonstrate still 

 more clearly the close affinity which exists between the Acanthocephala and the 

 Txniada— by proving the adult worm to arise by secondary growth within a hooked 

 embryo, in the former case as in the latter — leave some doubt upon the nature of 

 the reticulated canals. According to Leuckart, they are the remains of the cavity 

 which primitively lies between the wall of the embryo and the contained rudiment 

 of the adult Acanthocephalan body. 



