434 The American Naturalist. [May, 
“It was dredged in the laminarian, from 5 to 15 feet, attached to 
various Rhodosperms, as Ptilota, Chondrus and Rhodymenia. Cir- 
cumstances did not permit me to ascertain the medusoid form of 
this polyp, although I have my conjecture.” 
Prof. Hyatt’s sketches’ represent two 
. stages of development in the life history of 
this remarkable hydroid. One of these 
[ Fig. 3] is evidently of a younger and less 
. developed animal, possessing temporary 
tentacles which have a likeness to those 
figured by Allman in the immature Myrio- 
thela. We know from Allman that as the 
Myriothela grows older, the tentacles, which 
in this genus are known to belong to larval 
_ life, disappear, and are lost in the adult. 
Picking canis oo kaneis These are represented in our figure [Fig. 3] 
end of Acaulis, showing on the axis, about one-third the length of 
rmporary tentacles # (A. the young Acaulis, while the remainder of 
yatt, del.) 
the body bears simply suckers, which cover 
the surface of this region of its body. In the second figure [ Figs. 
1 and 2], which represents a larger individual, and one which is 
therefore probably more mature, two regions can be readily 
distinguished in the body, which we may call an anterior and a 
posterior body-region. The animal is represented as attached to 
a shell by suckers at the anterior end,—the broken parts of these 
organs are represented by dotted lines, as these appendages have 
been ruptured. In Prof. Hyatt’s notes, brown matter is mentioned 
as being found at the place of adhesion of these suckers to the 
foreign body. s 
For a short portion of the body adjoining the terminal tentacles 
its surface is thrown into folds or ridges (f), which are possibly 
due to mural contraction. From this region there arise botryoid 
bodies, which are supposed to be gonophores (g) or homologous 
structures, each of which has, according to the notes, a dark pur- 
ple interior and a granular whitish exterior wall. The remainder 

7Stimpson’s figures of Acaulis are the only ones yet published of this highly 
exceptional hydroid. 


