VAN NAME: SIMPLE ASCIDIANS. 
469 
of the body. To these processes a great quantity of mud and very 
fine sand adheres, giving the animal the appearance of a ball of mud. 
Mantle exceedingly deli- 
cate, so that it is difficult 
to remove it entire from 
the test. Mantle muscles 
poorly developed. The 
bands radiating from the 
bases of the siphons are 
neither numerous nor stout, 
and the circular bands un- 
derlying them are slender, 
irregular, and usually not 
closely placed. Some short 
transverse bands occur 
along either side of the 
mid-ventral region. 
Tentacles chiefly of three 
sizes or orders, quite regu- 
larly arranged, those of the 
first two orders apparently 
usually numbering six each, 
and those of the third order 
twelve. Tentacles of the 
fourth and fifth orders (the 
last merely small un- 
branched papillae) occur in 
the spaces between the 
larger ones, but are neither 
very numerous nor very 
regularly placed. The 
large tentacles have rather 
short branches, and only 
those on the basal half or two thirds of the main trunk bear small 
branches. Tips of the branchlets not at all enlarged. 
Dorsal tubercle clearly seen in one specimen only. In this it had 
an elongated very slightly curved slit-like orifice placed almost trans- 
versely. 
Dorsal lamina plain-edged anteriorly, but the margin of its posterior 
portion is, in some individuals at least, obscurely denticulate. 
Text-fig. 3. — Caesira liitulenta, sp. nov. Part 
of branchial sac of right side of a specimen from 
Station 921. X 12. 
