Polyzoa Entoprocta and Ctenostomata. 17 
to the oral and lateral surfaces of the stalk ; within the capitulum they meet at 
an angle with a pair of well-defined oblique muscular bands on each side. 
Type-species.— C/^i/as/)/s athleticus, sp. nov., from the Tale Sap, Gulf of vSiam. 
Closely allied as is the type-species to Loxosomatoides , the arrangement of its 
musculature is so conspicuously different that a new genus is necessary for its recep- 
tion. In this point it is different from all other Entoprocta as yet kn own. In Myo- 
soma the muscles of the stalk emerge from the capitulum in much the same way, but 
the oblique body-muscles are much less highly differentiated.^ In the resting buds of 
Urnatella^ and Loxosomatoides^ oblique strands of muscles occur, but no such struc- 
tures have been detected in the normal capitulum. The body-muscles described by 
Ehlers' in Barentsia {Ascopodaria) are by no means highly specialized and the stalk- 
muscles do not enter the capitulum. The Loxosomatidae are so different in other 
respects that no confusion is possible and discussion as to resemblances and differen- 
ces in the musculature is unnecessary here. 
Chitaspis athleticus, sp. nov. 
(PI. I, fig. I.) 
Colony. In the type-specimens the colony consists of a segmented, entirely 
adherent stolon that branches sparingly on the surface of a stone and gives rise at 
considerable intervals to single upright polyps. Polypiferous and non-polypiferous 
segments alternate with some regularity, the latter being by far the longer of the two. 
The lateral branches are given off, as a rule singly, from polypiferous segments of the 
stolon. The stolon is flattened below and evenly arched above ; it varies somewhat 
in diameter, but does not exceed 0*082 mm. Both stolon and polyps are covered 
with a rather thick chitinous investment which varies somewhat in thickness, but is 
not more than 0 0041 mm. thick; on the aboral surface of ths polyps this ectocyst is 
modified to form the aboral shield characteristic of the genus and of Loxosomatoides. 
Polyp. Each polyp consists of a short stalk bearing a relatively large capitulum. 
The stalk is rarely if ever longer than, and as a rule rather shorter than, the capitu- 
lum. It is relatively very stout and does not taper much above; there is no defined 
swelling at its base. The capitulum is rather broadly oval as seen from in front or 
behind; it is not much compressed. I^arge capitula are about 0374 mm. high and 
0*272 mm. broad. The diameter of the stalk may be as much as 0T7 mm. at the base. 
The normal number of tentacles is 18. 
The aboral shield varies considerably in extent but never encroaches on the oral 
surface. When fully developed it covers the whole of the aboral surface, and has 
well-defined limits. It never bears spines but is ornamented with a minute network 
of fine ridges that encloses polygonal depressions of somewhat variable size and out- 
line but never more than 0 051 mm. in greatest diameter. The ridges are slightly 
1 Robertson, Pfoc California Acad. Sci. (Zool ) II (3), p 324. pl- xvi, figs. 1-12 (1900). 
2 Davenport, Bull. Mus. Comp Zool. Harvard. XXIV, p. 24, pl. vi, fig. 57 (1893). 
3 Annandale, Mem. Ind. Mus. V, p. 130, fig. 2 (191 5). 
+ Ehlers, Abh. Kong. Gesells. Wiss. Gottingen (Math.-Natiirw. Kl.) XXXVI, p. 64, pl. iii, figs. 40, 43 (1890). 
