586 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
ventral surface, and having the small square apertures on low eleva- 
tions a little way apart on the upper surface. Outline of body when 
seen from above rounded or elliptical, 11 mm. long by 9.5 mm. broad 
in the largest specimen studied. Test thin and parchment-like, often 
nearly smooth to the naked eye, though finely wrinkled under mag- 
Text-flg. 40. — Dendrodoa carnea (Agassiz). X 4.2. 
nification, generally free from attached foreign material. (In old 
and large specimens the surface often is rougher and more or less 
coarsely wrinkled.) The test spreads out beyond the margin of the 
body on the surface to which the animal is attached forming a border 
often 2 mm. wide. This part of the test is penetrated by club-shaped 
vascular processes of the mantle. Color, when alive, pinkish to bright 
red, often appearing like a drop of blood ; in alcohol pale yellow or 
whitish. 
Mantle thin, with slight musculature. 
Tentacles mostly of two orders, arranged alternately with consid- 
erable regularity and numbering about 32; additional third-order 
tentacles are represented by minute tubercles in the intervals but are 
generally not sufficiently developed to deserve counting as tentacles. 
Dorsal lamina plain-edged. 
Dorsal tubercle small, oval, with an oval or elongated aperture 
whose long axis lies antero-posteriorly. 
Branchial sac with only one fold (the first) on the right side of the 
body and none on the left side. The fold on the right side usually 
bears four internal longitudinal vessels. Ventral to the fold are three 
more widely separated vessels each of which may represent a fold 
that has disappeared. On the left side of the sac there are generally 
only four widely spaced vessels. Assuming that they each represent 
the rudiment of a fold, the scheme of these vessels may be written as 
follows : 
Right side (4) (1) (1) (1) 
mdv. en. 
Left side (1) (1) (1) (1) 
