ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
575 
Ccelentera. 
Gastrodes.* — Herr K. TIeider, who lias had the opportunity of 
examining for himself the structure of this parasitic Ctenophore, essen- 
tially confirms the statements of Korotneff, its discoverer, regarding its 
structure and histology. The agreement with the young stages of Cteno- 
phores is such that he can find no obstacle to considering it as a parasitic 
Ctenophore, the development of whose apical sensory organ and ciliated 
plates has been suppressed in consequence of its mode of life. Its 
presence in Salpa appears to be the cause of sterility in the host ; how 
the parasite feeds is not certain, but it may be supposed to take up the 
nutrient juices diffused in the body of its host. 
Craspedote Medusse of the Planktoii.j — Dr. O. Maas adopts 
Haeckel’s general classification with a slight modification from Vanhoffen. 
He naturally gives precedence to the Trachylinae (Trachomedusae and 
Narcomedusae), which are pelagic forms par excellence , and has less to 
say of the Leptolinae (Leptomedusae and Anthomedusae). In dealing 
with species he has taken pains to utilise what is known of the ontogeny 
of the forms in question. 
Among forty-six species captured, the following are named as new : — 
Trachynema longiventris , Marmanema velatoides , Bhopalonema striatum , 
Aglantha occidentals or A. digitalis var. occidentals , Liriope distanogona , 
L. compacta, L. minima , L. hyperbolica , Solmaris multilobata, Pegantha 
dnctyletra , Cunina duplicata , Solmundella Hensenii , Halopsis megalotis , 
Ptychogena longigona , and Tiara prismatica. At least ten of these are 
certainly new species. Two new genera are also established — Homoeonema 
and Pantachogon , both included meanwhile within the family Trachy- 
nemidae. In the former the tentacles are all uniform, but, instead of 
being definite in number, corresponding to the radial canals, they are 
numerous (32-64 or more). In the more primitive and divergent 
Pantachogon the gonads are not localized in definite portions of the 
radial canals, but occur as irregular vesicles over their whole course ; 
the tentacles are numerous and uniform. Apart from the description of 
these new forms, Dr. Maas has many notes of systematic interest in 
regard to readjustment of generic limits and diagnoses. 
Of 126 Plankton-catches, 116 contained Medusae, and only 9 of the 
116 contained littoral forms; in 88 catches with the vertical net only 
18 included littoral forms ; in 18 of the same there was but one littoral 
form to 120 pelagic medusoids. In short, the thoroughly pelagic nature 
of the captures was conspicuous. Probably the more delicate muscu- 
lature of the sub-umbrella and velum unfits the coast forms for the 
open-sea conditions in which the medusoids with direct development 
flourish. 
In regard to the quantitative distribution of the Craspedota the 
author is cautious. More material is required. He gives tables, how- 
ever, showing certain facts, such as the absence of Medusae from the 
south point of Greenland to the Labrador Stream ; the very uniform 
distribution of certain forms, e. g. Bhopalonema velatum, over wide areas ; 
* SB. Ges. Nat. Freunde Berlin, 1893 (1894) pp. 114-9 (2 figs.). 
f 4 Die Craspedoten Medusen der Plankton-Expedition* Kiel u. Leipzig, 4to, 
107 pp., 6 pis., 2 maps, 3 figs. 
2 R 2 
