REPORT ON THE NEMERTEA. 101 



striction in the proboscis, which I observed in the longitudinal sections of the only specimen 

 of Carinina that had retained its proboscis. 



I cannot affirm that this constriction was natural, i.e., that it would also be found in 

 fresh specimens. Since, however, I have formerly described (VII) similar constric- 

 tions in the proboscis of Carinella and Valencinia, there are many a priori grounds 

 for also accepting its normal occurrence in Carinina. At the same time it more or less 

 coincides with the change in the character of the epithelium just noticed. 



The epithelium of the proboscis of certain Schizonemertea was known to be charac- 

 terised by the presence of nematocysts. In a former publication (VII) I showed that 

 the observation of Max Muller, who first noticed urticating elements in Cerebratulus 

 urticans, might be extended to nearly all Schizonemertea, although the size of these 

 elements is generally considerably below that of the type species just mentioned. 

 Muller has given good figures of the shape of the elements in his species ; of the others 

 no figures have hitherto been given, and fig. 2 of PI. XV. is intended to show the situa- 

 tion of packets of urticating elements, batteries, as they might be called, in a transverse 

 section of the anterior part of the proboscis, rather than to furnish particulars concerning 

 the histology of these nematocysts. They are seen to be situated close to the free surface 

 of the cells, and to be of different sizes on the dorsal and on the ventral surface of the 

 proboscis. Three batteries are figured lying free in the lumen of the proboscis ; when 

 seen from the side they have the aspect of a brush with close hairs seen in the same way, 

 when seen from above they appear to be more or less circular, and each of the elements 

 composing the battery is then found to be represented by a fine dot instead of by a 

 straight line, as was the case in the side view. 



In the spirit specimens of Cerebratulus more than these general facts could not be ascer- 

 tained. I may add that fresh specimens from the Mediterranean showed that each of the 

 elements out of which such a battery is composed has a spindle-shaped form, being more 

 or less pointed at both ends and somewhat bulging in the middle, and that from one of 

 the pointed ends — which in its natural position is directed away from the proboscidian 

 epithelium — the fine urticating thread may be observed to issue. This thread is, in most 

 cases, comparatively short. Whde in Cerebratulus urticans there is hardly any doubt 

 that each urticating element may act independently of the others, it is not improbable that 

 in some species, as the one here described, they remain connected in batteries by whose 

 joint action, when the proboscis is projected, delicate animals may be wounded or para- 

 lysed upon extrusion of the proboscis, and may thus fall an easy prey to the proprietor 

 of this formidable weapon. 



As to the more detailed histology of this epithelium, I wish to withhold further remarks 

 till I am enabled to publish the observations on the fresh specimens examined at Naples. 

 Similarly the curious and very adhesive epithelium of the foremost portion of the 

 Hoplonemertean proboscis which I have formerly described (IV, V), which was well 



