Miscellaneous. 187 
flattish epithelial cells, and then a thicker, transparent, elastic, and 
very extensile chitinous layer. 
From the end of the ductus ejaculatorius to the external opening 
of the sexual apparatus we have an uninterrupted chitinous sac, 
with various kinds of evaginations, folds, and thickenings. The 
upper portion of this section of the sexual apparatus, termed the 
“bulb” by Leuckart, is laterally compressed, and has beneath a 
delicate external membrane very columnar epithelial cells, beneath 
which there lies a tolerably thick laver of transparent colourless 
chitin, upon which on each side two large chitinous plates, which 
are fused together, are fixed. The chitin of these plates has a 
distinctly granular structure, and the clearer and softer the chitin, 
the more plainly are the granules visible. In the completely 
hardened places the granules cannot be seen at all, or only indis- 
tinctly. 
The portion of the genital sac which follows the bulb of the penis 
is so strongly chitinized that nothing is to be seen of the epithelial - 
cells. The chitin is thickly covered with stout simple (not branched) 
hairs, directed inwards, which are larger and thicker at those spots 
where there are evaginations and folds in the chitinous wall. These 
structures have, as everyone 1s aware, a mechanical importance in 
the act of coition, and have been described a thousand times, but 
never quite correctly. The exact description of these structures is 
out of place in a provisional communication, since too many details 
would have to be alluded to. I will only observe that, with the 
exception of the above-mentioned chitinous plates of the bulb of the 
penis, we find no plates in the entire genital sac of the bee, but 
only evaginations and folds of the chitinous wall. 
The detailed description of the genital apparatus will appear in 
the ‘Tageblatt der zoologischen Abtheilung der kais. Gesell. d. 
Naturw. Anthropologie und Ethnographie.’—Zoologischer Anzeiger, 
xiv. Jahrg., 1891, no. 3876, pp. 393-396. 
On the Free-swimming Sporocysts.” By M. Braun, 
of the Kénigsberg 1. Pr. Zoological Museum. 
The term “free-swimming sporocyst” has been applied by E. 
Ramsay Wright * and R. Leuckart ¢ to the single example which 
has hitherto been discovered of a certain developmental stage of a 
Distomum. I have observed numerous specimens in an aquarium in 
which I had shortly before placed various freshwater snails from the 
“bog” (“Bruch”) near Rossitten in the Kurischer Lowlands. 
While, however, the American species is only 1 millim. in length, 
the specimens from this locality are as much as 6 millim. long, and 
* American Naturalist,’ vol. xix. 1885, pp. 310, 311. 
+ Die thierischen Parasiten des Menschen &c., 2 Aufl. 2 Bd. pp. 102, 
108. 
