446 ZOOLOGY. 



formed of perforated zinc so as to admit the air. The food-plant or 

 object required for the suspension of the chrysalis, when that stage 

 of the insect is exhibited, is inserted into the case through a circular 

 hole iu the bottom; but the glass front also opens, so that ready access 

 may be obtained to the interior. The cases are arranged all along the 

 sides of the interior of the building as well as on two tables in the mid- 

 dle. The contents of the several cases are indicated by labels and sup- 

 plemented by mounted specimens of the corresponding species in its 

 various stages of development. The most conspicuous of the exhibits 

 are the large Bomhycidce, or silk-producing moths, which had been ob- 

 tained from their respective habitats iu the chrysalis form ; among them 

 were the American Samia cecrojpia and Samia Gloveri, and it was found 

 that the former selected the plum-tree and the latter the gooseberry as 

 favorite food-plants. 



The Periodical Cicada^ alias " Seventeen-year LocusV^ 



The well-known Cicada, which, from its periodical appearance, has 

 been designated as "The Seventeen-year Locust," is represented by a 

 form, which, according to entomologists, cannot be specifically diflereuti- 

 ated from it, but which differs in habits, appearing at intervals of only 

 thirteen years, and which has consequently been designated by Professor 

 Eiley as the Cicada tredecim. Certain broods of both of these forms 

 coincided in their appearance in 1881 : one of septemdecim had made its 

 last appearance iu numbers in the year 1864, and one of tredecim in 1868, 

 and the last simultaneous appearance of the two would therefore have 

 been in 1660. 



Alternate generation in the Gall Insects, 



In certain species of Cynipidse Dr. Adler has discovered that alterna- 

 tion of generation takes place, and that the same species in the two stages 

 may show such differences that the respective forms had been previously 

 referred to two distinct genera. The discovery was made through the 

 observation that N'euroterus laid eggs which gave birth to a form repre- 

 senting the genus Sjpatheogaster, such form being an agamic condition. 

 The organs of generation are nevertheless reproduced in the agamic 

 offspring, and the eggs are even developed generally in larger number. 

 It is noteworthy, also, that in the agamic form there is also a recepta- 

 culum seminis, but it is rudimentary: 19 species representing three 

 genera — Ncuroterus^ Dryoj)hanta, and Biorhiza — manifest alternation of 

 generation, but four others, of the genus Aphilothrix, do not develop the 

 agamic stage. These results are confirmatory of deductions by Bassett 

 and Kiley made in the United States about ten years ago. 



Peculiar glands connected with the Bee's Tongue. 



The common honey bee Avas being examined as to the structure of its 

 " tongue" by Mr. Justin Spaulding, when he discovered in the mentum 



