60 General Notes. [January, 
“alternation of generation” in Willia, raised by Dr. Brooks in 
the September number of the Naruratist. Lzzzta octopunctata 
produces young by budding from the time she is herself attached 
to the parent until she acquires the form as figured by Forbes. 
After that time reproduction by gemmation, in the restricted 
sense of the word, ceases, and a sexual method takes its place. I 
have studied one of these Lizzie in which the eggs had begun to 
form while yet buds were attached to the proboscis of the same. 
Can we not, therefore, instead of considering that there are two 
separate forms of Willia, one of which forms a new generation 
asexually, and another which reproduces by the egg, suppose, as 
is the case in Lizzia, that in the same individual, after the asexual 
method ceases, we have as final products of the somewhat simi- 
lar process, the formation of eggs which, after contact with the 
sperm, pass through a sexual development? 
If there are two forms of Willa ornata, they may be simply 
male and female. Was the “second form” of Willia, spoken of 
by Dr. Brooks, male or female? Before its sex is known, the 
theory of “ alternation of generations,” which he advances, is pre- 
mature, and when it has been shown that the “second form” is a 
female, it remains to be demonstrated that the asexual “ first 
form” does not ultimately develop into the second which lays 
eges.— ¥. Walter Fewkes, Cambridge, Dec. 6, 1880. 
Zootocicat Nores.—Prof. Ercolani has recently studied the 
placenta of cartilaginous fishes, and of mammals, with reference 
to classification and anthropogeny. Another Italian, Prof. Ciaccio 
as communicated to the Academy of Sciences of Bologna the 
results of his examination of the intimate structure of the eyes of 
Diptera, and also those of a blind Talpa. Mr. Swinton’s book 
on “insect variety” is not favorably reviewed by Nature ; though 
it is said to be full of original observations. It is devoted mainly 
to the subjects of mimicry, odors, dances, colors, music, and in- 
sect variation. A writer in Mature confirms Mr. Ober's state- 
ment in his ‘Camps in the Caribbees,” as to the singular habit of 
the gnat beetle, Dyzastes hercules, which seizes hold of a branch 
of a tree, and whirls around by its wings until the limb is severed. 
Mr. Ernst, of Caraccas, says the beetle wants to get at the abund- 
ant juice of the young branches. He adds that the Golofa porteri, 
an allied insect of the same family, behaves in a similar way, but 
chooses of course thinner branches. The Zoologischer Anseiger 
for November 1, contains the conclusion of Studer’s notice of | 
sexual dimorphism in Echinoderms. The structure of the 
poison apparatus of spiders has recently been studied by J. 
MacLeod of Belgium. About 7800 species of Heteropterous 
Hemiptera had been described up to the year 1879, while up to 
1859 about 3000 species of Homopterous Hemiptera had been 
catalogued. Mr. Uhler has estimated that there are probably 
not less than 10,000 species of North American Hemiptera. 
