ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
617 
quite young stages there are two rows of proportionately large oval or 
rounded vesicles, about fifty in number. In a succeeding stage there are 
only twenty-four, and in sexually mature individuals there are but 
scattered remnants left. In like manner the mature individual has not 
the two long pouches which are found at the base of the sucker in the 
young. The same species has not a cirrus-pouch, in the exact meaning 
of that term ; there is a muscular tube which appears to consist merely 
of muscular fibres. 
In all three species of Monostomum the author has discovered an 
organ which has not, apparently, been yet described. It lies round the 
excretory pore, and appears to be a part of the excretory apparatus. 
It forms large saccular diverticula on the terminal part of the efferent 
duct which lies in front of the excretory pore. Further details are 
promised. 
The large American Distomum.* * * § — Prof. R. Leuckart shows that 
Fasciola carnosa of Hassall f is not confined to America. He thinks 
that Distomum magnum , as Bassi called it, was brought to Europe by the 
Wapiti deer. 
Distomidae in Birds. :f — Prof. M. Stossich has made a monographic 
study of these parasites. He describes no less than sixty-four species 
of Polyorchis, Gephalogonimus, Gladocoelium , Grossodera , Distomum, 
Echinostomum, Mesogonimus, and Agamodisiomum, and notes fifty-seven 
doubtful species of Distomum. A useful index of birds is given with 
the Distomidae known to occur as parasites in the several species. 
New Temnocephala.§— M. A. Vayssiere’s researches on Temno- 
cepliala madagascariensis , a new species of parasite on the body of 
Astacoides madagascariensis, have led him to prepare a fresh diagnosis 
of the genus to which it belongs ; he accepts Semper’s view that the 
worm is a Trematod and not a Leech. 
Spermatogenesis of Trematoda.|I — Dr. F. S. Monticelli has studied 
this in Distomum megastomum and many other forms. In the young the 
testicles are uniformly filled with spermatogonia which are at first 
directly transformed into spermatocytes, while subsequently the latter 
originate by the indirect division of the spermatogonia. In older 
testicles the spermatocytes divide by ordinary karyokinesis and form 
spermatocytes of the second order. These adhere in pairs, the separation 
after division being incomplete, and each divides so that groups of four 
result, each of which again divides. Thus, eventually, there results a 
ball of spermatocytes, a sperm-morula, without a distinct cytophore. 
Finally, the spermatocytes composing the spermato-morula are differen- 
tiated into spermatides or young spermatozoa. Dr. Monticelli describes 
this last modification, which results for instance in the chromatin of the 
nucleus forming the head of the spermatozoon, but it does not differ 
essentially from what is true in many other organisms. Finally the 
* Centralbl. f. Bakteriol. u. Parasitenk., xi. (1892) pp. 797-9. 
t See this Journal, ante, p. 41. 
I Boll. Soc. Adr. Sci. Nat. Trieste, xiii. (1892) pp. 143-96. 
§ Comptes Rendus, cxv. (1892) pp 64 and 5. 
|1 Boll. Soc. Nat. Nap., v. (1891) pp. 148-50. 
