1884. ] Zoblogy. 1157 
tive individuals grouped around a nutritive individual. The last 
theory accounted for facts which could not Be explained by that 
of Haeckel. M. Perrier communicated the details of his re- 
searches upon the anatomy of adult Comatulæ. From these 
researches, based upon more than two hundred sections, it ap- 
pears that the organization of a Comatula is singularly like that 
of other echinoderms, notwithstanding the apparent wide diver- 
gence. If a sea-urchin is considered as a crinoid, the arms of 
disk, and the mouth of which is placed at the point of insertion 
of the disk upon the stem, the nervous and ambulacral systems 
will have the same relations as in the Comatula. It is worthy 
notice that at this spot the calyx of many crinoids is invaginated, 
and presents points nct without analogy with the dental apparatus 
of the sea-urchins. 
a communication made by Dr. Day to the Zodlogical Society of 
London (Feb. 5, 1884) it appears that an elongated Isopod (Con- 
ilera cylindracea), some of which attain a length of one and 
a-quarter inches, devour the soft parts of the dog-fish, muscles 
and entrails. On one occasion 100 dog-fish were netted,and “nearly 
every fish was found to have been eaten in a like manner by the 
lice.” These “ lice,” as the fishermen call them, “ in the summer 
months are found from fifteen to twenty miles from land, gener- 
ally on soft and sandy bottoms. When the fishermen in foggy 
weather get on this bottom, they call it ‘lousy ground,’ Where 
the lice are abundant they drive away the congers and other fish. 
Often a shoal of bream will come and eat them up.” 
part of the nest, but simply the result of digging.” On the coe- 
trary, I am convinced that the crayfish duds his chimney OF 
tower ; that he often studies the locality with care and ag Aad 
suit the chosen site. My reasons for this conclusion are: 
a large series observed during the present year were SO piore t 
a steeply sloping bank of a ditch, that if the materials of wii? 
the towers were composed had been simply reject agit ie 
nved from tunnelling, then it could have been rolled sie fas 
ditch without trouble, while in fact an artistic garners 
inches in diameter and varying from eight to eleven =n 
peight, was erected; and in several horace agora kried 
ower was specially provided for by having 
ane Semethea pee the picnic masses of puddled clay were 
