REPORT ON THE MYZOSTOMIDA. 
13 
remarkable are the cysts of Myzostoma tenuispinum (PL XIII. figs. 6 and 11-16), which 
consist of small fusiform oval chambers, arranged longitudinally or transversely, and 
formed by the enlargement of some of the brachialia or basalia ; these are extremely con- 
spicuous, since they do not become gradually flattened. A third group of malformations 
consist in independently formed cysts, i.e., cysts that are not produced by the transforma- 
tion of a pinnule or an arm-joint. These cysts appear upon the ambulacral surface, 
and are either sessile and of various forms [Myzostoma cysticolum, PI. XIII. figs. 1-3), 
or pedunculate and club-shaped ( Myzostoma murrayi, PI. XV. figs. 5-9). Myzostoma 
injlator (PI. XV. figs. 1, 2) produces both sessile and stalked cysts. 
Finally, there are compound cysts (PI. XIV. fig. 8), due to the approximation and 
fusion of the two different cysts formed by Myzostoma ivillemoesii and Myzostoma tenui- 
spinum, the latter on the arm -joint and the former on its pinnule. 
In the following Tables are given complete lists of the known species of Myzostoma 
and their hosts : — 
Table I. 
List of species of Myzostomida. 
Species of Myzostoma. 
M. horologium, n. sp. 
i 
t 
Host. 
Adinometra jukesi, P. H. C. 
„ strata, P. H. C. 
Received from. 
Challenger Expedition. 
Do. do. 
M. longipes, n. sp. 
M. cliinesicum, n. sp. 
M. labiatum, n. sp. 
M. echinus, n. sp. 
M. alatum, Graff. 
M. costatum, F. S. L. 
M. plicatum, n. sp. 
Uncertain. 
Uncertain. 
Anted on incequalis, P. H. C. ? 
Antedon incisa, P. H. C. 1 
„ incequalis, P. H. C. ? 
_ Adinometra mMfaWZfs,Liitken,MS. 
Antedon phalangium, Mull., sp. 
[ Antedon savignyi, Mull., sp., or 
j „ palmata, Mull., sp. 1 
„ triquetra, Semp., MS. 
_ Adinometra parvicirra, Mull., sp. 
Antedon tenax, Liitken, MS. 
“ Blake.” 
Dr. J. W. Spengel. 
Challenger Expedition. 
Do. do. 
Do. do. 
Copenhagen Museum, 
“ Porcupine.” 
Prof. v. Siehold. 
Prof. C. Semper. 
Do. 
Copenhagen Museum. 
