274 Macteay Memortat Vouume. 
organs are situated opposite the anterior part of the pharynx and are possessed of a 
horny centre, being smaller in the females and more like clefts. The stoutly built 
pharynx is supplied at the middle with an encircling ring ; in front of this ring it is 
longitudinally striated. The dorsal tooth reaches beyond the ring, and there are one 
or two others near the base of the pharynx. The median bulb is two-thirds as wide 
as the neck, while the cardiac bulb is an elongated swelling, not bulbous. The brown 
and somewhat tessellated intestine is marked off from the cesophagus by a distinct 
constriction ; it is said to be composed of not above three rows of cells. The rectum 
is three-fourths as long as the anal body-diameter. The ventral excretory pore 
occurs at 9%, that is, considerably in front of the cardiac constriction. The finely- 
pointed conoid tail is slightly concave somewhat behind the middle and bears a pair 
of lateral papillee (pores ?). This species is viviparous, the uteri sometimes containing 
a dozen embryos. The reflexed ovaries sometimes meet and cross. The proportions 
of the male are precisely those of his mate, but he is somewhat smaller, usually 
measuring only 2:mm. Papillse as follows: only one pre-anal submedian pair just in 
front of the anus ; three lateral equidistant pairs on the anterior half of the tail 
beginning near the anus; two pairs submedian opposite the lateral three pairs ; two 
pairs subyentral close together opposite the anterior pairs of the preceding two 
groups. The pores (?) found on the female occur also on the male. Spicula slender, 
arcuate, one and one-half times as long as the anal body-diameter. Accessory pieces 
one-half as long as the spicula, slipper-shaped, plump, and nearly surrounding the 
tips of the spicula. Synonym, D. fictor, Bastian. 
Hab.—-Found among fresh-water algze in Western Europe and England. Has 
the habit of becoming suddenly still, as if dead 
38 
ere: ~o : tb) Os) S65: 70° : . 
14. D. gracilis, Biitschli. =a-e— sa -¢- 9m = Neck convex-conoid ; body wider 
in the middle than at the vulva, namely 7:3 °/,; head rounded-truncate ; cephalic sete 
six ; lips six, broad and flat; pharynx cylindroid, composed of several horny pieces, 
with possibly two rudimentary teeth at base; both bulbs elongated, the median 
central, the cardiac weaker ; cesophagus twice, the bulbs three times, as wide as the 
pharynx ; intestine large, thin-walled, forming a shoulder in the cardiac region, 
separated from the cesophagus by a deep constriction so that the collum is only one- 
fifth as wide; cardia broad and distinct; cardiac cavity two-thirds as wide as the 
body and very long; rectum half as long as the anal body-diameter ; tail concave- 
conoid, diminishing in the anterior fifth to a width as great as the head, and thence 
conical to the hair-fine terminus; vulva inconspicuous, with almost invisible radial 
muscles ; vagina one-third as long as the body is wide; eggs same size as median 
bulb; ovary reaching at least three-fourths the way back to the vulva. The propor- 
tions of the male agree fairly with those of the female, but the tail is shorter. Papille 
