1890.] A Zoblogical Reconnoissance. 433 
“ ACAULIS, St. n. g, 
A. primarius, St. n. s., Fig. 4. The remarkable polyp for which 
this name is proposed, which is probably the largest hydroid 
known,° was observed at Grand Manan in two successive stages 
of development. It was first taken early in August, when it was 
of a sub-cylindrical form, tapering suddenly to a point at each 
extremity. At the upper extremity was the mouth, very small, a 
little below which the tentacula commenced, scattered at first, but 
gradually increasing in number, and somewhat in size. These 
tentacula were minute, very short, equaling in length about one- 
sixth the thickness of the body, with large globular tips. They 
occupied about two thirds of the body; on the remainder below, 
their places were supplied by the medusa buds, which were 
crowded, and much larger than the tentacula although as yet but 
little developed. The inferior extremity of the body terminated 
in a short, pointed, fleshy spike, free from appendages, from which 
exuded a tenacious mucus, by which it adhered to the subaqueous 
surfaces to which it might be applied. Around the base of this 
spike, and immediately under the buds, were regularly arranged 
eight long gracefully-curved cirriform processes, each equaling in 
length about half that of the body. These appeared from their 
motions to be in this—the first stage of the animal’s existence— 
the locomotive organs. 
“At a subsequent time I met with several of these animals 
which presented a different appearance. The tentacula were 
larger, especially in the region of the mouth, at the now blunt 
extremity of the body ; and the medusa buds were in an advanced 
state of development, soon to become free-swimming individuals. 
The inferior appendages had disappeared, and the body was firmly 
attached by a broad base, and bore much resemblance to one of 
the ordinary Corynidz deprived of its stalk. In strong contrac- 
tions it assumed a shape approaching an hour-glass. The length 
of the animal in this latter stage was half an inch, the breadth 
two-tenths. Inthe earlier stage the dimensions were one-half these. 
6 The pini added to the Hydroidea of the deep sea by the explorations of late 
when this was written by Stimpson. 

ae Nat. Mag —3. 
