330 
REPORT ON ZOOLOGY, MDCCCXLII : 
Comatulw (Bericht uber die zur Bekanntmachung gecigneten Verband • 
lungen der Konigl. Akad. der Wissenscb. zu Berlin, 1841, p. 179, and 
Arch. 1841, i. p. 139). He distinguishes twenty-four species, among 
which twelve are found with ten arms, the others are many-armed. 
Fifteen are new species, nine of them belonging to the many-armed. 
The Gomatulce want a madrepore-form plate. The sexes are separate. 
Muller never observed the cirrhi of the central tubercle (cup) move. 
He has also published an important contribution to the more exact 
knowledge of the Pentacrinus caput Medusae (Bericht, ant. cit. 1840, 
p. 88, and Archiv. 1840, i. p. 307). The stalk as well as the cirrhi 
of this Crinoid are without muscles, while the stalk of the young 
Comatuloe {Pentacrinus europceus, Thomps.) is contractile. The arms 
and pinnulse of Pentacrinus are furnished with muscles, which are 
situated on the abdominal side. The alimentary canal passes through 
the middle of all the parts of the skeleton. The furrows of the tentacles 
of the Gomatulce and Pentacrini are internally provided with two rows 
of very small tentacles. There are genera among the Grinoidece with 
and without an anus. The arms of the Gomatulce and Pentacrini have 
two canals, besides the vascular one, passing through the middle, namely, 
the abdominal- cavity canal and the tentacle canal; the five canals of the 
abdominal cavity open into it. The digestive organs lie in the disc 
under the skin ; the sexual parts, on the other hand, are in the pinnulse 
under the ventral cuticle. In the Grinoidce, the arm-rays always pass 
out from the dorsal part of the calix ; in the Asteriadce, the whorls of 
the rays pass from the ventral side. 
ACALEPH^. 
Agassiz has given a list of the systematic names of the genera of Aca~ 
lepJia in the Nomenclator Zoologicus (Fasc. i. 1842) ; much investigation, 
has been bestowed on this class during the past year, and the history 
of their development and metamorphoses proves, that several genera, 
hitherto recognised as distinct, are merely the young state of others. 
Currents have been observed by Patterson in the vessels, passing from 
the stomach and ribs of the Gydippe pomiformis (Trans, of the B. Ir. 
Acad. 1841, p. 91). The cilia of the eight ribs were seen by him in 
uninterrupted motion ; and, therefore, he considers them not merely as 
organs of motion, but also of respiration. He could not observe phos- 
phorescence in this Medusa, which he thought he did in Polina hiber- 
nica (ibid. p. 154). The ovaries, according to Krohn’s account, are 
to be found situated under the eight ribs (Fror. Neue Notiz. B. 17, 
p, 52). 
Milne Edwards found the ribbed Medusae described by difierent 
374 
