No. 397.] REVIEWS OF, RECENT LITERATURE. 74 
new species, Notropis muskoka, is described. This species is of the 
subgenus Chriope, an ally of N. cayuga. Etheostoma boreale, described 
by Jordan from Montreal in 1884, and not since seen, has been redis- 
covered by Dr. Meek in Gull Lake, near Lake Muskoka. jj ¢ j: 
Function of Vascular Ampullæ in Composite Tunicates. — The 
colonial blood vessels of the composite tunicates belonging to the 
family Botryllidæ often show a considerable number of terminal 
enlargements — the ampullæ. These are found almost anywhere 
within the colony, but are especially numerous along its edges. 
They have been regarded without much reason as developing 
zoóids, an opinion generally abandoned for several more recent 
views; namely, that they are reservoirs for blood, organs for the 
excretion of the test matrix, or for respiration. Dr. F. W. Bancroft 
has shown that they normally execute coórdinated pulsations, which 
continue, with some change in the coórdination, after separation from 
the rest of the colony. The rhythm of the ampullar pulsations is not 
affected by the reversals of the hearts in the zodids. The pulsations 
are very slow, and the contractile tissue seems to be a thin layer of 
pavement epithelium. Such coórdination as the ampulle show is 
brought about principally by blood pressure. In an estivating 
colony of Botrylloides gascoi, the circulation was kept up almost 
entirely by the ampulle. They must, therefore, be regarded as 
organs for the propulsion of the blood. Cur 
Sense Cells in the Integument of Worms. — L. Atherton? has 
made a study of the integument of the fresh-water worm Tubifex, 
with special reference to its nervous structures. The epidermis, 
beneath which there is no basement membrane, is usually a single 
layer of cells, produced apparently from the growing zone at the 
caudal end of the worm. Sensory cells of a spindle shape, or more 
swollen, occur isolated, in loose groups, or as well-defined clusters ; 
externally they are provided with sensory bristles, and internally they 
give rise to nerve fibres, which extend to the central nervous organs. 
Isolated sensory cells are numerous over the caudal end, sparse over 
the middle trunk region, and numerous again over the anterior part, 
where they may bear more than a single sensory bristle. Loose 
! Bancroft, F. W. A New dumme "s the Vascular Ampullz in the Botryl- 
lide, Zool. Anze: eiger, Bd. xxii, pp. 
? Atherton, L. The Epidermis of arii rivulorum Lamarck, with Especial 
Reference to its Nervous Structures, Anat. Anzeiger, Bd. xvi, pp- 497-509. 
