CLASSIFICATION 



Order II. Schizonemertea 



The proboscis is unarmed. The epidermis 

 the layer of connective tissue by a thin base- 

 ment membrane, hence the glands in the 

 connective tissue are more deeply situated 

 and have long ducts. The muscular layers 

 are three in number, an outer and an inner 

 longitudinal layer lietween which lies a layer 

 of circular muscles. The lateral nerve-cords 

 lie between the outer longitudinal and the 

 circular muscle layers. They are connected 

 throughout the body by a nerve plexus, the 

 only definite nerve branches given off Ijeing 

 those to the brain, oesophagus, and proltoscis. 

 The cephalic slits are a pair of deep longi- 

 tudinal grooves at the sides of the head. 

 From each groove a canal passes inwards 

 into a posterior brain - lolje. The mouth 

 opens behind the brain, and is an elongated slit 

 bounded by corrugated lips. Auditory organs 

 have not been observed. The longitudinal 

 vascular trunks are connected anteriorly by 

 lacunar spaces, and not by closed vessels. 



Principal British genera and species : 



is separated from 



FIG. 58. Head end of 

 Cerebrtttiilus margin- 

 a tits Ren., from the 

 ventral surface. 

 Drawn from a spirit 

 specimen. Naples, 

 x 1. c.s, Cephalic 

 slit ; m, mouth ; p.p, 

 proboscis pore. 



Linens lilineatus Ren., L. Inctcus Mont., L. marinvs Mont. ( = L. Inngix- 

 nmu-s Gunnerus), L. yesserensiis O. F. Miill. ( = L. obscurus Desor and L. 

 tunyuinetu M'lnt.). 



Tjorlntfiii elizttbetluie M'lnt. 



Ccrebratuliis anrjulatus O. F. Miill., C. /#* M'lnt., C. pantherinux Hubr. 



Alicrura aurantiaca Grube, M, caiulida Burger, M.fusciohita Ehrenb., M. 

 purjHtrea J. Miill. 



Mcckclia asulcitta M'lnt. 



Order III. Palaeonemertea. 



The proboscis is unarmed. The epidermis and connective 

 tissue form one layer, below which is the basement membrane. 

 The muscular layers are three in numl>er, two circular separated 

 by a longitudinal layer. The nerve-cords lie altogether external 



