os 
~~] 
1903. ] ANATOMY OF A NEW GEPIHYREAN WORM. 
The Generative Organs. 
Stretching across the ventral aspect of the celom, at the point 
where the ventral retractors are attached to the body-wall, is a 
band of cells with relatively large nuclei. These cells constitute 
the genital band and are derived from the peritoneal epithelium. 
In the single worm examined, neither free ova nor spermatozoa, 
were to be seen in the body-cavity. 
Systematic, 
The presence of hooks and the possession of four retractor 
muscles are characters which at once place Phascolosoma teres in 
the first of the five “ groups” into which Selenka (5) divides the 
genus. Atthe time of publication of his ‘ Die Sipunculiden’ three 
species alone (PA. vulgare, Ph. elongatum, and Ph. cylindratum) 
composed the group. To these must now be added, as well as 
Ph. teres, Ph. sanderi Collin (1) and Ph. lobostomum Grube 
(Fischer, 2). The position of Phascolosoma abnormis Sluiter (6) 
must in the existing state of classification remain doubtful, as the 
whole anterior end of the animal was wanting. 
The nearest ally of Ph. teres in the group is Ph. elongatwm 
(see Keferstein, 3). Both have the same arrangement of tentacles 
and the same number of rows of hooks, while the hooks themselves 
are very similar. Lh. teres, however, differs widely in the pro- 
portionate length of its introvert, and, as regards its imternal 
anatomy, in the small size and unequal bulk of the nephridia, in 
the absence of any definite spiral coiling of the intestine, in the 
great length of the hind-gut, and in the absence of a spindle- 
muscle; and, as well as in these particulars, in its characteristic 
habit of body. From every other member of the group except 
Ph. cylindratum it differs in the complete absence of papillie. 
These peculiarities warrant the systematic zoologist in assigning 
to the animal under discussion a distinct place in the genus, and 
I propose for it the name of Phascolosoma teres. 
That the genus Phascolosoma is an eminently variable one is 
evident to any investigator who makes a systematic study of the 
Sipunculide ; and that this tendency to variation may result in 
the inclusion in one small sub-group of animals which differ in an 
astonishing extent in external habit, is abundantly exemplified 
by the fact that Phascolosoma teres and Ph. sanderi (Collin) two 
worms so dissimilar that a casual observer would be pardoned for 
placing them in different genera—must yet, in the present rather 
unsatisfactory state of classification, be united in the group called 
by Selenka “ Group I.” of the Plisiscolosomidas : yet, while the 
latter was considered by its describer Collin to present points of 
resemblance to that curious Sipunculid Goljingia macintoshii (8), 
and seems to have points in common with <Aspidosiphon, the 
former appears to me to present in its structural peculiarities 
definite affinities to the sedentary Phascolion. NRoule (4), who 
