Dr. Johnston’s Index to the British Annelides. 437 
7. P. stagnalis. 
Fasciola stagnalis, Mull. Verm. i. ii. 53. 
Planaria stagnalis, Mull. Zool. Dan. Prod. 221. Templeton in Loud. 
Mag. N. Hist. ix. 239. 
8. P.macrocephala, oblonga, fusca, antice dilutior truncata, postice 
attenuata; oculis ocellisve nullis; long. corp. 2lin. Pl. XV. fig. 2, a,b. 
Hab. Amongst Conferve in Berwick bay. 
Desc. Body brown, oblong, truncate before and paler coloured, narrowed 
posteriorly ; no eyes nor eye-like points. The anterior extremity, in some 
positions, appears marked with a pale subcircular spot, while in others a 
light-coloured line runs down the centre, while the margins seem folded in 
so as to form almost a tube, as is well represented in our figure 6. From 
this circumstance I conclude that the worm is thin with involute margins, 
but I never saw it spread itself out. There are two ventral pores, similar 
to those of the genuine Planarie. 
I have named this species macrocephala because of the bluntness of its 
head, for the enlarged end is the anterior one, a fact which the mere exami- 
nation of the figure would never resolve, since the part is distinguished by 
none of its usual appendages or organs: it has neither mouth, eyes, nor ten- 
tacula. But all unfurnished as it is, there is no species of its genus that I have 
met with that excels it in activity. Ever-restless, it glides along the sur- 
face of the vessel with great celerity, varies its course with ease, and some- 
times leaving the bottom, it swims in the bosom of the water, but with a 
tardier pace. With the obtuse anterior end, which is in constant motion 
and change, it feels the way, and pushing aside the floating particles that 
annoy it, it guides itself with as much safety, and appears as careful of ob- 
stacles as if indeed eyes and feelers were sentinels in front. 
9. P. Hirudo, lineari-elongata, fusca, antice puncta lineaque nigra 
signata; maculis supra caudam orbicularem duabus pallidis. Long. 
corp. 4 lin. Pl. XV. fig. 3. 
Hab. The sea amongst Conferve. 
Desc. Body linear, lengthened, brown, marked in front with a black point 
and line; two pale spots above the circular tail. Length 4 lines. 
This little worm was also found in Berwick bay, and it is little less active 
than the preceding. It glides along in a continuous motion, and when in- 
clined to turn or change the direction of its course, it forms the tail into a 
disc-like sucker to give itself the advantage of a fixed point. The body is 
of a uniform light brown colour excepting the two pale spots near the tail, 
and, when fully stretched, is of a narrow linear figure, slightly tapered in 
front. There is asmall black dot about haif a line behind the anterior end, 
and a dark line runs from it forward to the tip. These are not formed by 
an eye, or a cluster of eye-like points, but the line seems rather to be pro- 
duced by some internal tube, and the dot by some harder, perhaps horny, 
substance. 
This worm is of a doubtful genus. The black stria at the anterior end 
may perhaps indicate the existence of a proboscis; and the soft disc at the 
tail has some resemblance to the sucker of a leech. I retain it in the genus 
Planaria because the body is smooth without trace of wrinkles or rings, and 
because there are two obvious pore-like spots near the posterior extremity. 
The specific name, however, may serve to mark its affinity to some of the 
leech tribe. 
** Freshwater. 
10. P. nigra. 
Planaria nigra, Mull. Zool. Dan. Prod. 221. Zool. Dan. iu. 48. 
