VAN NAME: SIMPLE ASCIDIANS. 
519 
regular network with almost rectangular meshes covering practically 
the entire body, formed by long slender bands radiating from the 
siphons, crossed at right 
angles by other bands 
placed at quite regular 
intervals. 
Tentacles of three sizes, 
arranged according to the 
usual scheme (1, 3, 2, 3, 
1, 3, 2, 3, etc.)- There are 
about eight of the first and 
eight of the second order. 
The tentacles are peculiar 
in being all entirely un- 
branched, but they are 
provided, as in other mem- 
bers of the Caesiridae, 
with a broad membrane 
extending along their 
whole length. Dorsal lam- 
ina a rather narrow mem- 
brane whose free edge is 
plain or very obscurel;)' 
and minutely sinuate. 
Dorsal tubercle small, 
with a simple C-shaped 
orifice the horns of which 
are neither inrolled nor 
strongly incurved. The 
open interval was toward 
the left in two out of three 
specimens, and toward 
the right in the third. The 
endostyle is narrow. 
The branchial sac is of very delicate structure, and has no true folds, 
though six folds on each side are indicated by six longitudinal rows, 
each of eight large flattened infundibula, bridged over by one or more 
longitudinal vessels (see text-fig. 22). The infundibula show little if 
any of the tendency to divide into two apices that is common in this 
Text-fig. 22. — Caesira singularit 
of left side of Ijranchial .sac. X 12 . 
, sp. nov. Part 
