Juny 5, 1918] 
Zoological and Allied Subjects 
(a) Bird records of the past winter (1917- 
1918) in the upper Missouri valley. (b) A note on 
molluscan behavior. (c) Birds of Union county, 
South Dakota: T. C. STEPHENS. 
An unusual example of incisor growth in the 
western fox squirrel: DayToN STONER. 
Pharyngeal derivatives of Amblystoma: FRANCIS 
MarsH Bautpwiy. This paper deals with the 
morphogenesis of the thyreoid and thymus glands, 
the postbranchial and epithelial bodies of Ambly- 
stoma, beginning with larve 5 mm. long, and in- 
eluding stages in metamorphosis and adult. The 
thyreoid gland arises as a solid outgrowth from 
the pharyngeal floor and breaks up into scattered 
cells, which, by mitotic division, give rise to the 
thyreoid follicles, in which colloid appears in late 
larve. There is no evidence of the formation of 
accessory thyreoids. The thymus gland arises from 
five pairs of anlagen, derived from the dorsal mar- 
gins of the corresponding gill pouches. The an- 
terior two degenerate, the other three form the 
definitive organ. There are no ectodermal contri- 
butions to the gland. The postbranchial body 
arises from a thickening of the pharyngeal floor, 
behind the last gill-pouch. In all cases, with one 
exception, it was asymmetrical. At the time of 
metamorphosis two pairs of epithelial bodies arise 
from the ventral parts of the last two gill pouches. 
They are the homologues of the parathyreoids of 
the mammals, 
Economic entomology and food conservation: R. 
L. WEBSTER. 
A list of the birds found in Marshall county, 
Iowa: Ina N. GABRIELSON. 
Notes on a wood borer: H. E. JAQuEs. 
The influence of floods upon animals: D. M. 
Brumrizut. This paper is an analysis of the ways 
in which floods may affect animal life based upon 
observations made along Whitewater river in 
Fayette county, Indiana. Floods affect animal 
associations in two general ways, viz.: (1) by 
changing the habitats topographically, and (2) by 
changing the composition of the association with- 
out affecting the physical habitat. 
Topographical changes may be brought about as 
follows: (1) the course of the stream may be di- 
rectly altered, (2) the local character of the stream 
may be altered, (3) changes may be brought 
about in the flood plain. 
Floods influence associations directly by: (1) 
destroying or removing forms already established 
and (2) providing a means of dispersal. 
SCIENCE 23 
The life and behavior of the house spider: H. E. 
Ewine. Although the common house spider, 
Theridion tepidariorum K., is one of the most 
common arthropods observed about our houses no 
one in the past appears to have made a systematic 
and thorough study of its life and behavior. 
The complete life history is given, and observa- 
tions extending over a period of several years are 
here reported. Scores of individuals were ob- 
served daily for many months both in eaptivity 
and in their natural environment. The cocooning 
process is described and illustrated by figures. 
Notes on courtship, cannibalism, food habits, emo- 
tions, instincts and intelligence are given. 
A preliminary list of the Acarina of Iowa: 
ALBERT HarTZELL. But few lists of Acarina have 
been made in this country. In 1886, Professor Os- 
born and Professor Underwood published a pre- 
liminary list of the Acarina of North America. 
This list included 99 species and 28 genera. In 
the Iowa list here given 75 species and 55 genera 
are included. 
The mite fauna of Iowa is in general very simi- 
lar to that of Illinois, yet it is interesting to note 
that in the vicinity of Ames we find several of the 
northern forms. No records of sheep scab or hu- 
man scabs have been noted in recent years. Sheep 
scab at one time occurred in this state, but due to 
the efficient work of the United States Bureau of 
Animal Industry it apparently has been eradi- 
cated. 
Notes on the food of the yellow perch in Cayuga 
Lake: W. A. Horrman. This paper consists of 
preliminary work relating to the food of the yellow 
perch, Perca flavescens Mitchill, which was done in 
the limnological laboratory of the department of 
entomology at Cornell University. 
Twenty-one fish were seined on two days, June 
25 and July 14. An examination of the stomach 
contents of these perch was then made. Crustacea, 
fish and fish eggs were found in the greatest num- 
bers and volume. Of the Crustacea, Decapods rep- 
resented by Cambarus were present in eight stom- 
achs, while Amphipods which consisted mostly of 
Gammarus and Hyalella were in ten. Chironomids, 
Trichoptera and Odonata made up most of the in- 
sect food. Only two Ephemerida were found, 
whereas these insects often are the only food to be 
found in the perch. The remainder consisted of 
Gastropoda, Hydrachnida and Entomostraca. 
The cranial nerves of the dogfish: Sauty P. 
HUGHES. 
Spiders of the family Attida collected in the 
vicinity of Ames: I. L. RESSLER. 
