8-2 
VINE: CARBONIFEROUS AN'D PERMIAN POLYZOA. 
functions. In Crisia we have good examples of the latter, wliile in 
the inflated surfaces of Hornera we have examples of the Gonocyst. 
In Idmonea, but very few species have been referred to or described 
having Gonocysts, but in several species of Diastopora, both fossil and 
recent the modified cells are common. " The Gonocyst has only been 
noticed in certain Cyclostomatous genera, it is probably only a modi- 
fication of the Gonoecium. Of the history of these structures, 
however, we know little, they remain to stimulate and reward further 
research."* 
I am not certain whether I should call all the structures now to 
be referred to, Gonocysts, but after quoting the above passage from 
Mr. Hincks, the student will be furnished with an authoritative 
opinion concerning them. In plate iii., figs. 10 and 11, I have given 
an example, unique in some respects, of a Gonocyst of CystodkUja 
parallela, PhilL, or what I regard as such. In fig. 10, a portion of 
the Zoarium is enlarged for the purpose of showing its exact position 
on the side or margin of the frond. The same is enlarged about 60 
diameters in fig. 11, and drawn with camera lucida, by which means 
details of structure are also given. Originally the Gonocyst appeared, 
that is before it was sectioned, as a roundish tubercle on the edge, 
partly covering a portion of the striated margin of the specimen. 
In the section, which has been carefully worked so as to get near the 
centre, the Gonocyst appears to have been formed under the ectocyst 
of the Coenecium, and consists of a vesiculate chamber having a 
nearly circular opening. On the inner side it is attached to, and 
forms part of the marginal vesiculate edge, while just beyond it are 
the oblong bases of the cells up to the first bar. In plate iv, figs. 
15 and 16, the Gonocyst of Goniodadia celliilifera, Eth. Jun., is 
giveii by way of comparison. The structure is of a similar character 
with that of C. iKvrallela, but the difference is sufficiently noticeable 
to indicate that we are dealing with different species, but the family 
likeness is at once apparent. In plate iv., figs. 18 and 26, there are 
two examples of Gonocysts given, one figured and enlarged about 30 
times, as a rather long excrescence on the margin, having a small 
orifice towards the top (f. 18), while in the other (f. 26), we appear 
* Brit. Mar. Polyzoa, p. xcvi. 
