502 A. E. Verrill — Marine Planarians of New England. 



twelve to eighteen arise from each of the posterier divisions [g'). 

 Those in the middle part of the body are mostly two-lobed or 

 forked, and some of them ai'e divided into three or four branches 

 but some remain simple, especially toward the ends of the body. 

 Under pressure all the branches usually appear lobulated along their 

 sides and at their ends. The posterior trunks also give off from 

 their inner borders smaller lateral branches which run in toward 

 the median line, where those of opposite sides anastomose, back of 

 the pharyngeal region. The two posterior trunks do not anasto- 

 mose at their posterior ends in any of the examples studied by me. 

 The anterior trunk terminates behind the brain. 



The pharynx (/") is large, cylindrical or urn-shaped, according to 

 its state of contraction, lobed or scolloped at the end, and often 

 plicate or grooved along the sides. It is often protruded in alco- 

 holic specimens. 



The bilobed brain (c) is large and easily seen. Each lobe gives 

 off from its antero-lateral and front borders about five main nerves 

 (c') which subdivide and run to the margins of the head. The 

 main lateral nerve-trunks (n, n') are large and distinct. They run 

 back and anastomose directly in the posterior sucker. They give 

 off, all along their course, lateral nerves that subdivide into many 

 small branches, part of which go to the adjacent organs, while some 

 go to and join the small but distinct marginal nerve («"), in the 

 vicinity of which tliey form a fine network. The principal trans- 

 verse branches from the large nerve-trunks correspond nearly in 

 number with the gastric branches. Back of the genital organs 

 five or six, or more, transverse commissures unite the main nervous 

 trunks. The eyes are well developed, Avith a blackish, reniforra? 

 pigmented retinal body and a frontal lens-like structure. 



The genital orifice ( ? , 3 ) is situated just back of the pharyngeal 

 region. The vasa deferentia (d) run alongside of the pharyngeal 

 region as convoluted tubes; near the penis they become enlarged 

 and serve as two seminal vesicles (r). The penis-bulb is pyriform 

 or obconic, and the penis [jy) is simple, styliform. The oviducts 

 run forward from the female genital duct or vagina (v) on each 

 side to the germaria or ovaries (o, fig. 8), which are situated well 

 forward at or near the bases of the third and fourth pairs of gastric 

 branches. The vitellaria or yolk-glands are very numerous; they are 

 clustered around and between the gastric branches, together with 

 the testes or spermarian folicles (t, t), which are smaller and more 

 numerous. 



