64 LIVERPOOL BIOLOGICAL SOCIETY. 
contain twenty-six species of Simple Ascidians, some of 
them represented by a large number of specimens. 
Of these twenty-six species, thirteen have been identified 
as belonging to species already known and described. Two 
of them belong to the interesting genus Boltenia, namely, 
Boltenia gibbosa and B. pachydermatina, the latter species — 
containing some of the largest known specimens of Simple 
Ascidians. Ours, however, were only of moderate size. 
The other eleven known species are Microcosmus julini, 
M. variegatus, M. afinis and M. distans, Cynthia grandis 
and C. preputialis, Styela gyrosa and S. sqwamosa, Poly- 
carpa tinctor, P. longisiphonica and P. viridis. 
Boltema gibbosa was described by Heller,* who makes 
no mention of spicules in the test. Our specimen, how- 
ever, shows numerous calcareous spicules in the test, 
which vary in shape from simple bars to stellate figures 
(Bie Vries tie, 2). 
We have also found in the transverse vessels and internal 
longitudinal bars of the branchial sac of Boltena pachy- 
dermatina spicules which resemble those which seem so — 
highly characteristic of the nearly allied genus Cwleolus, 
but no reference has ever been made to the occurrence of 
these kinds of spicula in the genus Boltenia. In shape 
they are generally fusiform, occasionally bifurcating, or 
even assuming a tri-radiate form (Pl. VIIIL., fig. 1). This 
Boltenia is apparently a common species in Southern 
Seas, and specimens of it have long been known in 
museums, but it had never been examined until lately, 
when it was first described and named by Professor 
Herdman, in his Report on the “‘ Challenger”’ Collection. 
Since then it has been made the subject of further 
investigation by Dr. R. von Drasche.t 
* “Sitzb, k, Akad. Wiss.,” Bd. lxxvii., 1878. 
+ ‘Denksch, k. Akad, Wiss.” Wien, Bd. xlviii., p. 370, 1884, 
