208 
ROBERT SCHARFF. 
The latter evidently acts as a sort of protection to the fine 
hairs, and is analogous to those of Priapulus and Halicryptus. 
Langerhans 1 and also Solger 2 give further details as to their 
composition. The latter says : “ Two parts may be readily dis- 
tinguished in longitudinal sections — firstly, an outer integu- 
ment, and secondly, an inner nucleus. The former is con- 
structed of several layers of long cylindrical cells. These 
mantle-cells surround the second inner part which form a 
group of club or pear-shaped cells (Kolben oder birnformig 
gestalteten Zellen) (see Langerhans, pi. xxxi, figs. 10, 11, 12). 
The latter correspond to Bugnion’ s 3 “ cellules pyriformes ” 
and to the pear-shaped cells in Halicryptus. Bugnion’s 
“ cellules-a-batonnet ” would then be analogous to an internal 
group of cells I described (see also Bugnion, pi. xiii, figs. 
1, 3, 6). Moreover, Merkel, 3 in his very detailed description 
of the sensory organs of Vertebrates, points out that the set of 
cells surrounding the hair-cells secretes a sieve-like “ mem- 
brana limitans/’ through the meshes of which the hairs project 
into the surrounding medium. A similar limiting membrane 
was described above with regard to Priapulus and Halicryptus 
(fig. 1 and fig. 3 a, m.). This furnishes us with an additional 
point of similarity between the sensory organs of these two 
Gephyreans and the corresponding structures of the lower 
Yertebrata. 
The Nervotjs System. 
The results I obtained as regards the nervous system agree 
in general with those of Horst. It is composed of a ventral 
1 Langerhans, “ Ueber die Haut der Larve von Salamandra maculosa,” 
* Archiv f. Mikrosc. Anatomie, 3 vol. ix. 
2 B. Solger, “ Zur Kenntniss der Seitenorgane der Knochenfische,” ‘ Cen- 
tralblatt d. medic. Wiss.,’ 1877, p. 818. 
3 E. Bugnion, “ Sur les organes sensitifs,” * Bulletin de la Societe Vaudoise 
des Sc. nat.,’ vol. xii, p. 268. (Dissertation inaugurale.) 
4 Merkel, ‘Ueber die Endigungen der sensiblen Nerven in d. Haut d. 
Wirbelthiere, 3 Rostock, 1880. 
