72 THE AMERICAN NATWYRALIST. [Vor. XXXIV. 
groups of sensory cells are found on all regions of the body except 
the anterior end. Well-defined clusters are found only on the 
prostomium and first few segments. He 
The Eyes of the Polyphemida. — The eyes of the family of 
minute crustaceans, the Polyphemidz, have been the subject of 
careful investigation by Dr. O. Miltz.! The eyes are compound, and 
each retinal element or ommatidium is composed of two distal cells, 
forming part of the corneal hypodermis, of five cells forming the 
cone, of two supporting cells, and of a group of five retinular cells. 
The nerve fibres pass centrally from the retinular cells. The devel- 
opment, physiology, and biological significance of the eyes are con- 
sidered. G. HP. 
Zoülogical Notes. — An Uncinaria from a panther that died in 
the Königsberg Zoo has furnished Cohn (Arch. de Parasitol., Vol. IL, 
No. 1, pp. 5-22, 1899) with some important data on the life history 
of these forms and the injuries they produce. An introductory dis- 
cussion clears up the synonymy and shows that three good species 
occur in the Felide. The form studied, U. perniciosa, was found 
abundantly in small, dark-colored nodules in the wall of the small 
intestine, each nodule containing a number of individuals, among 
which the females were more numerous. A histological study of 
these nodules showed that they always lay in the submucosa, which 
‘was enormously thickened at that point at the expense of the circular 
muscle layer, and that each opened into the intestinal lumen by a 
small pore at which the epithelium was inturned. Larva much like 
those of U. duodenalis, recently described by Looss, were numerous 
in the intestinal mucus, and a single older form was met between 
the villi. In the nodules, on the other hand, only sexually mature 
individuals were found, together with the eggs. Cohn outlines the 
life history as follows: There is no secondary host, but the larva 
are brought directly into the intestine of the primary host, and when 
they have reached a certain period of growth they invade the wall of 
the canal and cause there the growth of nodules. The results of 
other investigators are interpreted in the light of this work which 
conforms, moreover, to the conjecture of Railliet in the case of 
Sclerostoma equinum. 
1 Miltz, O. Das Auge der Polyphemiden, A Bd. xi (1899), ERER 4 
pp. 1-60, Taf. I-IV. 
