Calliobdella nodulifera (Malm 1863). 121 
Their nuclei are large, and flattened in the same manner and direction as the 
cells. The large dermal cells are embedded in a matrix of connective tissue 
cells, among which are numerous fibre-forming cells more conspicuous than 
in other genera. The most striking feature of the derma is the occasional 
occurrence of large pigment cells, which are about 40p in length, almost as 
large as the large dermal cells. The pigment is yellowish-brown, and the 
leech can be recognised by the pigment cells when viewed by transmitted 
light, after the whole specimen has been cleared in oil of cloves. The colour 
does not dissolve in alcohol, and is preserved in the sections. Below the 
derma lie the muscle layers, which consist, as in most leeches, of one row of 
circular muscles, one row or so of oblique muscles, and some three rows of 
longitudinal muscles, below which are the cocoon-gland cells, concerning 
which I have nothing further to add to the description of them which I have 
already given in the case of Platybdella. In Callwobdella they attain the 
same huge and remarkable size as in Platybdelia, viz. 200-150» by 100-150p. 
Amongst these cells run the cocoon-gland cell ducts interspersed with 
longitudinal muscle fibres in the proportion of three of the former to one of 
the latter. 
Ca@Lom.—The body cavity consists of the five following parts, which can 
be well seen in Plate V. :—a dorsal sinus, a ventral sinus, two lateral sinuses, 
and, in the cecum region of the abdomen, an intestinal sinus. The dorsal 
blood-vessel is for the greater part of its length inside the dorsal sinus, but in 
the cecum region it lies outside and dorsal to it, the intestinal sinus being 
between it and the dorsal sinus. The ventral blood-vessel is outside the 
ventral sinus, and dorsal to it. This is not so in C. lophiz, and constitutes a 
specific difference. The ventral nerve cord is within the ventral sinus. The 
intercommunications of the sinuses can be best seen from Plate V. 
GENERIC CHARACTERS.—See Parasitology, vii. pp. 215 and 217. 
SPECIFIC CHARACTERS.—The body is not so flattened, nor is the neck 
marked off so distinctly from the abdomen as in C. lophi. The body is 
bestrewn with yellow dots due to the presence of characteristic pigment-cells, 
which are more numerous than, and are of a different colour and character 
from, those in C. lophit. The posterior sucker is twice the size of the anterior. 
According to Hesse the eggs are oval, while those of C. lophii are spherical. 
The ventral blood-vessel is outside the ventral sinus. Not confined to one 
host, but appears to show a preference for the Gadide. 
[EXPLANATION OF PLATES. 
