REPORT ON THE NEMERTEA. 55 



situated of the two latter layers of similar though much shorter glandular cells (PI. IV. fig. 1 ; 

 PL VI. fig. 2, E), immediately contiguous with others of a larger size, makes it a subject 

 for inquiry whether these are connected by transitional forms to those larger ones which 

 form the layer we are now describing. This involves the not unimportant question, 

 whether the glands constituting this layer are or are not unicellular. While I am inclined 

 to accept the latter proposition, I feel that the question can only be solved by the aid of 

 a careful inquiry into fresh specimens. 



The layer external to the glandular is one in which very numerous and deeply stained 

 nuclei are heaped together. These nuclei occupy several rows in one section. The same 

 may be said to apply, as will be indicated further on, to the corresponding layer of deeply 

 staining nuclei in the integument of the Hoplonemertea. 



The very outermost layer bearing the cUia clearly contains, in Carinina, the same 

 elements as will be described more in detail {TO(ie infra, pp. 58, 61) for the Schizonemertea, 

 i.e., nervous end-ceUs, alternating with supporting cells, " Stiitzzellen." 



This layer, containing fewer nuclei and less granular protoplasm, is more transparent in 

 transverse sections, and distinguished by fine radial striae, indicating the boundary lines 

 between the contiguous cells. The four layers here described are not equally distinct in all 

 sections, nor are they equally well marked in all the sections figured. Thus, for example, 

 in fig. 4 of PI. III. the glandular layer is feebly developed, and the two external layers are 

 so indiiferently preserved that their distinctive character, just described, fails to attract 

 attention. The chief points enumerated can, however, even there, be easdy ascertained. 

 The partial absence, or, at any rate, temporary indistinctness of these gland-cells in certain 

 portions of the integument can also be observed in tangential sections, such as the one of 

 PL III. fig. 8. There, too, the groups of glandular cells to the right and the left are 

 separated by a band of integument, in which they are decidedly absent. The same figure 

 shows the difi"erent ways in which the contents of these gland-cells react on staining 

 agents ; those to the right in this section have decidedly yellowish contents, whereas the 

 contents of the group on the left had a deep carmine tint. 



This description of the integument of Carinina must now be followed by that of 

 Eupolia, the only other genus of Palseonemertea contained in the Challenger collection. 

 The interesting genera Carinella, Cephalothrix and Carinoma, are not represented 

 in those collections and certain intermediate characters displayed by these genera, which 

 serve to justify the identification of the different layers, which as I am going to propose 

 can only be touched upon as far as they elucidate the phenomena. This I will defer 

 tUl after the detailed description of the integument of E^ipolia. 



Instead of four layers it would not be difiicult to distinguish eight in the integument 

 of this genus, not all of them separately and clearly represented in every section, but 

 sometimes {e.g. PI. VII. fig. 5, 9) sufficiently distinct. This arrangement may be looked 

 upon as a further difierentiation of an earlier phase, corresponding to that of Carinina, 



