12 THE AMERICAN MONTHLY [January, 



writer maintains that tliis fluid is intended mainly to prevent the coagu- 

 lation of the proteids of plants which the animal sucks from the tissues, 

 and that its poisonous efl'ect upon other animals is only secondary. 

 If so, it would perhaps follow that it is not introduced into the h.uman 

 flesh as a poison. It is difficult to see what purpose the irritating 

 effect of the bite upon other animals can serve the mosquito, since it 

 must make the chances of its getting nourishment from the blood of 

 other animals many times less than it otherwise would be. It may be 

 worthy of inquiry whether the irritating effect is not incidental and per- 

 haps only occasional, and due to other causes than the fluid which 

 seems, by analogy, to have another distinct purpose. The bite of the 

 mosquito is ordinarily extremely irritating to the writer, but under 

 many circumstances this effect is entirely wanting. My house is on the 

 border of a wood, through which flows a sluggish stream, and the re- 

 gion is infested with mosquitoes, the bite of which is exceedingly poison- 

 ous. During the cold evenings of summer these pests enter the cellar 

 windows through the course netting with which they are stopped, and 

 occasionally find their way into the living rooms. I have noticed that 

 these rarely give me any trouble from their bites I am not able to 

 offer any explanation, but cannot see why these should have less power 

 to use their poison glands, if such they are, than those which attack me 

 upon the piazza. 



Haplodiscus piger, Weldon. — Mr. W. F. R. Weldon, of St. John's 

 College, Cambridge, describes in ^uar. Jour. Mic. Sci. (vol. xxix, p. 

 i) a new organism, to which he gives the above name, found by him 

 occasionally in a tow-net near New Providence, Bahamas. It is 1.3 

 mm. long by i . i mm. broad, having a general resemblance to a proto- 

 zoan, but possessing a structure which indicates its relationship to tlie 

 worms. Mr. Weldon is uncertain as to its systematic position, but 

 seems inclined to place it among the Cestodes. 



Blastopore of Rana temporaria. — Mr. Harold Sidebotiiam, in the 

 same journal (vol. xxix, p. 49), gives the result of his studies upon the 

 embryo of the frog {Rana temporaria)^ in which he shows that the 

 anus does not rise from the persistance of the blastopore, but from a sepa- 

 rate invagination, and that the neural folds do not enclose the blastopore, 

 as maintained respectively by .Spencer and Balfour. • 



Mesozoic Mammalia. — H. F. Osborn, of Princeton College, gives 

 (Jour. Acad. N. vSci., Phila., vol. ix, No. 2) a very valuable review 

 of the characters and relations of the mesozoic mammals of America, 

 Great Britain, and other countries, with figures illustrating the subject, 

 and new facts and figures relating to the American species. The an- 

 imals were all small, the length varying from half an inch to an inch 

 and a half. Prof. Osborn sustains the view that they are not all mar- 

 supial, but that placental mammals are included, probably the insecti- 

 vora or their predecessors, and that marsupial and placental mammals 

 have not successional but parallel genetic relations. — Aw. Jour . Sci. 



