252) A. A. W. HUBRECHT. 
between the longitudinal muscular ones. This layer is very 
conspicuous in the Drepanophorus species, and consists of 
longitudinal columns, surrounded and united by bands of 
fibrous elastic tissue which at the same time traverse the 
longitudinal muscular coat in all directions, and originally 
depart from the external and internal circular layers of 
elastic tissue. (Plate XIII, fig. 6.) 
These columns seem to consist of a very homogeneous 
tissue, no cut ends of fibres being visible in vertical sections, 
and carmine solution, which was strongly imbibed by the 
elastic tissue, never tinged them in the least. The curious 
flask-shape of these columns in yertical sections at first 
led me into the error of regarding this layer as a complex 
of small glands. 
Iam much in doubt as to the muscular character of the 
circular layers ef, andz f, which are held as such by Mr. 
MacIntosh. The longitudinal layer 7 m,is decidedly mus- 
cular, traversed by a meshwork of interlaced elastic tissue as 
remarked above. Neither dol wish to follow Mr. MacIntosh 
in regarding the external and internal portions of this layer as 
two distinct muscular coats. 
Externally this part of the proboscis, when extruded, is 
covered with thickly-set papille, which are composed of fine 
translucent rods sticking together. They produce a gela- 
tinous mucus, and render the proboscis in a high degree 
sticky. A separate papilla is figured, Plate XIII, fig. 7. 
The structure of the stylet region, central and lateral 
stylets, is treated in extenso by Mr. MacIntosh. I only wish 
to point out the curious difference existing in this respect 
between Drepanophorus (n. gen.) and all other Nemerteans 
hitherto known. Instead of the usual transparent, straight, 
central stylet, with its swollen base and the peculiar mus- 
cular arrangement surrounding it, these species carry a 
crooked, dark-brown hook, pointed at the anterior, blunt at 
the posterior end, and held in position by a ring-shaped 
internal elevation of the proboscidean wall. A special mus- 
cular development in this region and natural stylet sacs are 
totally absent, a reservoir filled with a greenish fluid as wellas 
traces of an ejaculatory duct being visible. 
Something analogous was very vaguely described by M. 
De Quatrefages for his Cerebratulus spectabilis, but neither 
Max Schultze nor Mr. MacIntosh (who incorporates the 
species in his genus Amphiporus) believed in the correctness 
of the observations. ‘lhe finding of three new species present- 
ing a nearly similar stylet-shape confirms the validity of M. 
De Quatrefages’ statements. 
