666 The American Naturalist. [July, 
Distribution of Magelona.—Dr. E. A. Andrews calls atten- 
tion ê to the existence of the adult worm Magelona at Wood’s Holl, and 
points out that the larva described by Fewkes from Newport as pos- 
sibly the young of Prionospio tenuis in all probability belongs to this 
genus. 
Budding in Polyzoa.—C. B. Davenport, contrary to Hatschek, 
says’ that the stolonic mass in the Polyzoa arises from the ectoderm 
soon after the two-layered stage, the disc thus forming sinking below 
the general surface, and giving rise later to the first polypides. The 
ccelomic epithelium arises by a sort of ingression of a tissue to be 
probably regarded as mesoderm plus entoderm. In Paludicella each 
young polypide arises in the adult colony independently of any older 
polypide. It arises from a mass of embryonic tissue at the end of the 
branch, and some of this tissue is left behind each time the tip moves 
forward, and from this arise the lateral branches. As in the Phylacto- 
lcemata, the hinder part of the alimentary canal progresses from the 
anal toward the oral end. The cesophagus arises independently, and 
the two pockets fuse. The tentacles at first lie in two parallel rows o 
seven each, and the ectoproctous condition is not attained until the two 
free ends of the ring canal become confluent between mouth and anus. 
The so-called epistome described by various authors in early stages of 
Gymnolzmata has no relation with the similarly named structure in the 
other forms, but is merely the fold separating the brain cavity from 
the cesophagus. Eight laws of growth are formulated, based upon 
Bugula and Crisia as*typical. 
The Crystalline Style.—This problematical structure in the 
alimentary canal of many Lamellibranchs has recently been inves- 
tigated anew by F. E. Schulze.” The idea that it is a supply of reserve 
food material is rejected by him, from the fact, among other reasons, 
that microscopic study shows it to be an epithelial secretion. He is 
rather inclined to the view that it, along with the mucous surfaces of 
the stomach, protects the intestinal walls by covering sand and other 
sharp particles with a layer of mucus. 
The Position of Limulus.—Packard contiues his studies of the 
brain of Limulus." He claims that the brain differs fundamentally 
from that of Arachnids, and is homologous with only that part of the 
scorpion brain which lies in front of the chelicral nerves. The his- 
8 me ents Hopkins Univ. Circ., X., p. 96, 1 
rts and Sciences, x. 278, 1891. 
wie B. Ges Naturforsch. Freunde, 1890, p. 42. 
it Zool. pn ae X., 129, 1891. 


