Introduction to A niuial Morphology. 



imperforate, rounded, or facetted, and has 2-4 round or 

 elongated, sometimes movable, suckers (Fig. 23,3), and 

 may be armed with hooks of chitin (calcified or silici- 

 fied ?), acting as anchors, placed often alternately in 

 circlets. The blunt ends of these are in pouches, and 

 tlit -ir roots thicken with age. There are fine hairs on the 

 head and suckers in Triaenophorus, and on the hinder 

 end of the body in Tetrarhynchus. The head may 

 have a central spur (rostellum, cupula), or, as in 

 Tetrarhynchus, a Fig. 23. 



protrusible pro- 

 boscis, armed with 

 hooks. Behind the 

 suckers are occa- 

 sionally nerveless 

 red specks,perhaps 

 rudimental eyes. 

 The head is borne 

 on a neck which 

 begins narrow, but 

 rapidly widens into 

 the jointed body, which (except in Caryophyllaeidae) is 

 made up of 2-00 metameres. The body grows from 

 tin- head (the oldest part) to the distal end, so that the 

 mctann'n's are the newest, and the oldest joints 

 hose most remote from the head. Each segment 

 as it ripens develops reproductive organs, and is 

 named proglnttis, in which stage it may have a brief 

 t'-iico. As the immature sr^mt'nts 

 Mia show an int^r-mrtanu-ral continuity of 

 textures, and as th-p- ingle \vatrr-\ .isrular and 



(\vhrn present i tan, tlur entire worm is 



rsona, not as a colony. 



A. Proglottis of T. solium ; n, \\-ritrr-vascular 

 : b, sexual orifice; c, uterus ; </. t. 



males; f, vas dcferens ; B, head ol 

 T. nn-dio-canellata. 



