CLASSIFICATION 



I I I 



Order II. Schizonemertea. 



The proboscis is unarmed. The epidermis is separated from 

 :he 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 between 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" being 

 those to the brain, oesophagus, and proboscis. 

 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 - lobe. The mouth 

 opens behind the brain, and is an elongated slit Fl0 58._Head end of 

 bounded by corrugated lips. Auditory organs Cerebrakdusmargin- 



\ % , r _. . * ; { * atus Ren., from the 



have not been observed. Ihe longitudinal ventral surface. 

 vascular trunks are connected anteriorly by 

 lacunar spaces, and not by closed vessels. 

 Principal British genera and species : 



Drawn from a spirit 

 specimen. Naples, 

 x 1. c.s, Cephalic 

 slit ; vi, mouth ; p.p, 

 proboscis pore. 



Lineus bilineatus Ren., L. lacteus Mont., L. marinus Mont. ( = L. longis- 

 simus Gunnerus), L. gesserensis O. F. Mull. ( = L. obscurus Desor and L. 

 sanguineus M'lnt). 



Borlasia elizabethae M'lnt. 



Cerebratulus angulatus O. F. Mull., C. fuscus M'lnt., G. pantherinus Hubr. 



Micrura aurantiaca Grube, M. Candida Burger, M.fasciolata Ehrenb., M. 

 'purpurea J. Mull. 



Meckelia asulcata 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 number, two circular separated 

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



