658 THE ANIMAL KINGDOM. 



face, that beneath which the testes lie, is, judging from the analogy of the 

 Trematoda, considered to be dorsal ; the other, to which the vagina is 

 approximated, and on which the genital apertures are sometimes situated, 

 as ventral. 



There is a cuticle, with a subjacent layer of transverse elastic (? mus- 

 cular) fibres, a layer of vertical fusiform cells, and a more or less granular 

 matrix, which forms the bulk of the substance of the body. This matrix 

 imbeds cells of various kinds, nuclei, and the muscles of the body. It is 

 traversed by irregular lacunae, generally held to represent the coelome. 

 The muscles form one or more longitudinal layers, and an inner circular 

 layer, inclosing a core of matrix in which lie the main nerves, excretory 

 vessels and genitalia. There are also dorso-ventral fibres ; see pp. 225-6. 

 The whole worm is endowed with an extraordinary power of contraction 

 and extensibility. For the calcareous bodies which are absent in the 

 proscolex, see p. 227. 



The nervous system of the Taeniadae, so far as is known, conforms more 

 or less closely to that of T. serrata (p. 226). It is always situated in the 

 anterior part of the head. It consists in Bothriocephalus latus, in another 

 species of the genus parasitic in the dog, and in Ligula of a transverse com- 

 missure, containing ganglion cells in the former, and of two inconsiderable 

 lateral ganglia from which a stout lateral nerve passes backwards on each 

 side. In B. latus each lateral nerve gives origin to eight nerves which 

 accompany it, four on either side. The principal nerves give filaments to 

 the layer of subcuticular cells. Isolated ganglion cells have been said to 

 occur in the lateral nerves ; so too ganglionic swellings in each joint (p. 226). 

 There are no organs of special sense. The pigment specks seen on the 

 head of the scolices of certain species of Tetrarhynchus or on the neck of 

 Echinobothriuni) do not appear to be degenerate viscual organs 1 . 



The excretory system has been found, wherever it has been accurately 

 investigated, to consist of ciliated funnels appended to delicate canaliculi, 

 of main longitudinal canals with or without an intermediate network of finer 

 canals. Ciliated funnels (p. 581) are found in all parts of the body, but most 

 plentifully in a zone superficial to the central core of matrix, or in T. lineata 

 within the layer of circular muscles. The canalicules may unite inter se, 

 and open either conjointly or separately into a superficial network of fine 

 canals, e. g. in Tetrarhynchus, Bothriocephalus, Caryophyllaeus, or directly 



1 The ganglia of Sohnophorus appear to be differently arranged to what they are in other 

 Cestoda. See Griesbach, A. M. A. xxii. 1883. The ' plasmatic canals ' of Sommer, found by him 

 in T. solium and T. mediocanellata, are perhaps to be identified with the lateral nerves. See note, 

 p. 515, Z. W. Z. xxiv. 1874. The nerves from the ganglia of T.plicata are said by Rhemberg to end 

 in the cuticula as delicate threads, terminated each by a slight swelling (Arch. f. Thierheilkunde, iii. 

 J ^77> P- 43)- Sensory nerve endings and motor nerve endings have been described by Schiefferdecker 

 (J. Z. viii. 1874, pp. 475-480). But the results of these two observers have not been as yet confirmed 

 by others. , 



