188 On new Genera of Deep-sea Nemortines. 



pitted externally to receive the bases of epidermal cell 

 (PI. VIII. tij^. 3). It may be described as coiisistitiij^ of two 

 distinct zones. Of these the inner is much the thicker and 

 lias a finely fibrillar structure. A few small nuclei are visible 

 in this layer. The outer layer has a stratified appearance, as 

 though it had been secreted by the epidermal ceils which lie 

 upon it. The layers of which it is formed lie parallel to its 

 surface. The stratification is marked out as a series of 

 deeply stained bands alternating witii thicker layers of a 

 clear hyaline material. 



The circular muscle-fibres lie immediately below the 

 basement-membrane, and next to them are the longitudinal 

 fibres. These form a continuous layer, not broken up into 

 fascicles, as is the case in Pelagonemertes. 



Within the muscular system is the parenchyma, here 

 greatly diminished in bulk by the numerous branches of the 

 gut wliich lie in it. The parenchyma is traversed by bundles 

 of nerve-fibres. 



My sections, which were cut from a part of the body about 

 3 cm. from the hinder end, give no indication of the sex of 

 the individual. 



Bathynemertes Alcocld has the appearance of being a 

 bottom-living species, unlike Dinonemertes and the other 

 genera referred to the Pelagonemertidje, which have all of 

 them the characteristics of pelagic creatures. 



Literature. 



['87] HuBRECHT, A. W. AV. — Keport on the Nemertea collected by 

 H.M.S. ' Challenger.' ' Challenger' Report, Zoology, vol. xx. 

 (1887). 



['92] Verrill. — Trans. Connecticut Acad., New Tlaven, viii. (1892). 



['99] WooDwoKTH, W. McM. — Bull. Mus. Comp. Zool., Cambridge, 

 Mass., xxvii. 



EXPLANATION OF PLATE VIIL 



Fig. 1. Dinoneimrtes investigatwis. A., anterior; P., posterior end of 

 body. 



Fig. 2. Bathynemertes Alcocki. n, constriction at neck. 



Fig. 3. Part of a transverse section of liathi/nemcrtes Alcocki. e, epi- 

 dermis ; i', outer zone of basement-membrane; 6^, inner zone 

 of basement-membrane ; cm., circular muscle-fibres ; l.m., 

 longitudinal muscle-fibres. 



Figs. 1 and 2 about natural size. 



i 



