HYDROZOA ACRASPEDA. 789 



includes Auretia. (3) Rhizostomae : mouth obliterated ; four oral arms divided into 

 eight ; edges of their grooves united, leaving funnel-shaped apertures ; four sub- 

 genital cavities separate, Toreumidae, e.g. Cassiopeia, and Pilemidae, e.g. Pilema, or 

 united to form a syndemnium, Versuridae, e.g. Cotylorhiza, and Crambessidae. 



Claus, in the Arb. Zool. Inst. Wien, vii. p. 109, divides the sub-class as follows: 



I. Tetrameralia : with four radial sectors. 



Orders (i) CalycozoaDfpastridae and Lucernaridae : (2) Marsupialida, in- 

 cluding Charybdaea and its allies. 



II. Octomeralia : with eight sectors. Order Discophora with two sub-orders : 

 (i) Catammnata, with persistent septal unions 1 including Haeckel's Pero- 



medusae and Cannostomae : (2) Acatammnia, with no septal unions, but with a 

 gastral lamella and the oral angles prolonged into arms, subdivided into (a) Mono- 

 stomeae ( = Semostomae) and (b) Rhizostomeae. 



For the families he refers to his Untersuchungen, pp. 24 and 60. 



Haeckel, System der Medusen, Dk. med. wiss. Gesellschaft, Jena, i. pt. 2 and 

 Atlas, 1879; Id. Deep-sea Medusae, Challenger Reports, iv. 1882, p. 48; Claus, 

 Untersuchungen iiber die Organ, und Entwick. der Medusen, Leipzig, 1883; Id. 

 Dk. Wien. Akad. xxxviii. 1878; cf. for points of Anatomy, O. and R. Hertwig, 

 Organismus der Medusen, Jena, 1878, and Nervensystem und Sinnesorgane der 

 Medusen, Leipzig, 1878; L. Agassiz, Contributions to the Nat. Hist, of U. S., iv. 

 pt. 3, Boston, 1862. 



Lucernariae and their allies, Clark, Smithsonian Contributions to Knowledge, 

 1878; Craterolophus Tethys, Kling, M. J. v. 1879. Charybdaea marsupialis, Claus, 

 Arb. Zool. Inst. Wien, i. 1878. Nausithoe, Claus, Untersuchungen, &c., (supra], 

 p. 24 ; Aurelia, (= Medusa auritd], Ehrenberg, Akalephen des Rothen Meeres, 

 Phys. Abhandl. Akad. Berlin, 1835 ; ditto, Chrysaora, &c. (and development), Claus, 

 Dk. Akad. Wien, xxxviii ; Aurelia, Cyanea, Pelagia, Stomolophus, Polyclonia, L. 

 Agassiz, Contributions, &c. (supra] Cyanea Annaskala, von Lendenfeld, Z. W. Z. 

 xxxvii. 1882; C. arctica, Wagner, Wirbellosen des Weissen Meeres, Leipzig, 1885, 

 p. 83. Cassiopeia polypoides, Keller, Z. W. Z. xxxviii. 1883, p. 632; Rhizostoma 

 Cuvieri, Pilema pulmo, Brandt, Mem. Imp. Acad. St. Petersburg (7), xvi. 1871 

 metamorphosis of ditto and of Cotylorhiza, Claus, Untersuchungen, &c. (supra], p. 43, 

 and Arb. Zool. Inst. Wien, v. 1884; Pseudorhiza aurosa, von Lendenfeld, Z. A. v. 

 1882, p. 380 ; Ps. Haeckelii, Haacke, Biol. Centralblatt, iv. 1884-85, p. 291 \ 

 Crambessa Tagi, Grenacher and Noll, Abhandl. Senckenberg Ges. x. 1876, and 

 Greeff, Z. A. iv. 1881. 



Oral arms of Rhizostomae, Hamann, J. Z. xv. 1882. 



Monstrous forms of Aurelia, Romanes, J. L. S. xii. 1876, p. 527; xiii. 1878, 

 p. 191, with two plates ; Ehrenberg, op. cit. supra, p. 199, and PI. II. 



Development of genitalia in Lucernaria, Craterolophus, Charybdaea, Aurelia, 

 Discomedusa, Chrysaora, Claus, Untersuchungen, &c. (supra\ p. 39 et seqq. ; cf. 

 p. 88; cf. also O. and R. Hertwig, J. Z. xiii. 1879, p. 599 et seqq. Formation of 

 sperm in Cassiopeia borbonica (= Cotylorhiza tuberculata\ Merejkowski, A. Z. Expt. 

 x. 1882. 



1 By septal unions (Septalknoten) Claus appears to mean from p. 27 of the Untersuchungen, 

 four interradial spots to the outer or abaxial side of the gastral filaments where the exumbrellar and 

 subumbrellar layers of endoderm have fused : cf. note 2, p. 784, and note, p. 786, ante. 



