40 DR. W. BAIRD ON A NEW EARTH-WORM. [Jan. 14, 
doubled upon itself so as to make a perfect square, and sewn up so 
that two contiguous sides are closed, and two open, the closed sides 
being behind and below, and the open sides above and in front. 
The two upper free borders are connected with strong rods, 
moving upon one another at the angle when the net is opened or 
closed. At the lower and anterior angle a weight, generally consisting 
of a perforated stone, is appended, and the apparatus is complete. 
With this net one or two men dive into a deep part of the river, near 
a bold shore; immediately also some others disappear, and, having 
remained a considerable time under water, pop their heads up one 
by one, after which the net is drawn up on a shingly bank with the 
Ika loa floundering within it. 
DESCRIPTION OF PLATE TI. 
Fig. 1. Lateral view of Gonostomyxus loa loa (the type specimen is contained 
in the Haslar Museum). About one-third of the natural size. 
2. Inferior aspect of the head, with the mouth open to show the cresentic 
palatal membrane and the sucker-like plicated band within the border 
of the lower lip. 
3. A scale from the shoulder, magnified about 8 diameters to show its 
ctenoid character and the mucus-grooyve on its deep surface. 
3. Description of a new Species of Earth-worm (Megascolex 
diffringens) found in North Wales. By W. Bairp, M.D., 
F.R.S., &c. 
The genus Perichata was formed by Schmarda to include a number 
of species of earth-worms differing from the more common genera 
in having each segment of the body marked in the centre by a narrow, 
raised rim, which is beset, for the whole circumference of the body, 
by a row of spines or setze. He describes, in his ‘ Neue wirbellose 
Thiere,’ four species, all natives of Ceylon. In 1845 Dr. Templeton 
characterized a new genus of earth-worms, natives also of Ceylon, 
which he called Megascolex. This genus consisted at that time of 
only one species, a native of the alpine regions of that island, and is 
distinguished, like Pericheta, by a row of small spines or sete sur- 
rounding each segment. This row, however, according to Dr. 
Templeton’s description (see Ann. & Mag. of Nat. Hist. vol. xv. p. 
60) is not completely circular, the setze being deficient in the mesial 
line of the back for about the tenth of an inch. Schmarda, who 
considers the two genera distinct, does not quote Templeton’s de- 
scription accurately ; for he seems to think that that naturalist de- 
scribes the ridges on each ring as occurring only on the back; 
whereas he distinctly says they surround the body, only that the 
rows of bristles are not continued round the whole circumference, 
but are deficient for a short space on the back. 
In describing the genus Pericheta, Schmarda says that the species 
he describes possess no cincture or girdle, whereas in P. cingulata 
