HYDROZOA AND CTENOPHORA. 
GceL 3 
19. Haacke, W. Zur Blastologio der Gattnng Hydra^ specielle und 
gonorollo Studion zur Morphologic und Entwickclungslohre. Jon. 
Z. Nat. xiv. pp. 133-153, 2 pis. 
20. Hteckel, E. Ueber die Organisation und Classification dor Acras- 
peden. SB. Jen. Ges. 1880 (Feb.) ; Kosmos, iv. pp. 310-317, 
21. . Ueber die Organisation und Classification der Biscomedusen, 
Ibid. 
22. . Ueber die Acraspeden-Arten dos Mittelmeeres. Ibid. 
23. . Das System der Medusen, Erster Theil einer Monographic 
der Medusen. Zweite Hiilfte des Ersten Thiels ; System der Acras- 
pedeu. Denk. Ges. Jena, 1880, 672 pp., Atlas, with 20 pis. 
The present volume deals with the Acraspedote Medusce. Acraspeda 
are defined as Medusce possessing gastral filaments (phacellse), with endo» 
dermal gonads devoid of true velum (often possessing pseudovelum 
[velarium]), with true marginal lappets to the umbrella, devoid of a 
double centralized nerve-ring. Phylogenetically descended in all pro- 
bability, and ontogenetically, in some cases (though not at the present 
day in the majority), from Scyphopolypes with gastral filaments or from 
Scyphistomoe. Ontogenesis generally with alternations of generations (in 
the form of Strobilogenesis), often with direct development. The sexual 
Acraspedoto generation develops by terminal budding from the asexual 
Seyjdiistoma generation, Acraspedce may, according to Hreckel, be 
divided into two grades : — I. Tessero7iice, Hck. Acraspedce sometimes ^ 
devoid of, sometimes possessing, four tentaculooysts. Stomach with four 
wide per-radial enteric pouches, which are separated by four inter-radial 
knob-shaped or ridge- shaped septa. Generative glands (or gonads) 
bursal (in the sub-umbral wall or in the cavity of the enteric pouch), 
with centrifugal growth. Umbrella highly arched, generally conical. 
Phylogenetic type (and probably endogonetic larval form). Tessera. 
Contains — i. Stauromedusce {Staurojnedee, Becherquallen, Hck., 1878). 
Acraspedce devoid of tentaculooysts, j with four horseshoe-shaped genera- 
tive glands (or four pairs of ad-radial generative ridges) in the wall of the 
sub-umbrella or of the four enteric pouches. Inter-radial septa of the 
enteric pouches sometimes four simple knobs, at other times four long 
ridges, .ii. Peromedusce (Peromedee, Taschenquallen), Acraspedce with 
four inter-radial tentaculooysts, with four pairs of sausage-shaped genera- 
tive glands in the sub-umbral wall of the ring sinus. Inter-radial septa 
of the stomach pouches, four small, simple knobs ; the enteric pouches 
communicate therefore with a large ring sinus, iii. Cubomedusce {Cuba- 
medee^ W urfelquallen). Acraspedcey^iih. four per-radial tentaculocysts, with 
four pairs of flattened generative glands, which project freely into the 
cavities of the four stomach pouches. Inter-radial septa of the enterio 
pouches, four long ridges. The other grade are — II. Ephy^'ionice^ Hck. 
Acraspedce with eight or more tentaculocysts (four per-radial and four 
inter-radial), and, in addition, frequently other accessory tentaculocysts. 
Stomach with eight, sixteen, thirty-two, or more enteric pouches (or 
radial canals instead). Generative glands or gonads, gastral (in the sub- 
