304 
Florence Peebles. 
there is no bursa, and under the Convoliitidae those possessing this 
organ. The latter family he subdivides into those with one genital open- 
ing (Otocelis), and those with one or two genital openings, the feniale 
in front of the male. Monochoerus illardatMs and Monochoems lineatus 
will then be contained in this last division. I shall therefore identify 
Monochoerus lineatus as an Acoela with a bursa seminalis, one genita! 
opening, the mouth-piece lamellate, and opening into the parenchyma. 
It is distinguised from Monochoerus illardatus not only by its external 
form and markings, but by the absence of the female genital orifice. 
3. Ämphiscolops fuligineus, n. sp. 
a) External appearance. 
As Ämphiscolops fuligineus so closely resembles the green form 
Ämphiscolops cinereus, described by von Graff (1891), I shall limit my- 
self to a brief account of the more important anatomica! features, and 
omit the detailed description of the finer structure. Ämphiscolops fuli- 
gineus is a larger worm than either of those described in the preceeding 
pages, its size exceeds that of the Neapolitan form of cinereus. When 
the body is extended in swùnming the length is more than twice the 
breadth, but when in a contracted state the worm is almost square in 
outhne. When fully extended the largest worms measured from 2,00 to 
3,00 mm in length, and from 0,8 to 1,2 mm in breadth. At rest they 
assume the characteristic shape indicated in pi. 3, fig. 16. The deep 
depression between the ear-like projections of Ämphiscolops cinereus is 
here replaced by a rounded anterior end, and instead of a tail filament 
like that found in Polychoerus caudatus, there is a knoblike projection 
on the posterior end. This slight enlargement is due to the terminal 
Position of the large penis. The animai is capable of great Variation of 
form; when swimming it is cylindrical, but when partially contracted 
the dorsal surface is convex, and the ventral fiat. The edges do not turn 
under ventrally. 
The brown color of this worm is its chief distinguishing feature, 
therefore the specific name fuligineus, was selected. This pecuhar shade 
of brown is found in Saccardo's (1894) list of colors. The vivid contrast 
produced by the brown and white markings is striking, and this sturdy 
little robber is easily detected when swimming in clear water, but like 
Monochoerus lineatus, it is protected by its resemblance to the seaweeds 
upon which it is so often found. The anterior end of the body is entirely 
white, and for this reason the eyes and statocyst are plainly visible. The 
