970 



THE VOYAGE OF H.M.S. CHALLENGER. 



I. Subfamily 



Zygostephanida. 

 Four lateral gates (no 

 basal gate). 



II. Subfamily 



Acantliodesmida. 

 Five large gates (four 

 lateral and one simple 

 basal). 



III. Subfamily 



Eucoronida. 

 Six large gates (four 

 lateral and two basal). 



Spiojysis of the Genera of Coronida. 



Two meridional rings ] 



(sagittal and frontal) I -p, i . i , • i 



^ ° 1 , ' r our lateral gates simple, 



complete, perpen- 1 or; 



,, , 11 Four lateral gates partly latticed, 



another (no basal | o i- j > 



ring). J 



Two meridional rings 

 (sagittal and frontal) 

 incomplete, botli 

 truncated by the 

 complete horizontal | 

 basal ring. J 



Two rings (the sagittal 

 meridional ring and 

 the horizontal basal 

 ring) complete, the ' 

 frontal meridian 

 ring incomplete. 



Four lateral gates simple, 



Four lateral gates partly latticed. 



Basal ring 



without larger 



descending 



feet. 



Gates simple, . 



Gates partly lat- 

 ticed, 



Basal ring witli large, regularly 

 disposed, descending feet. Gates 

 simple, 



414. Z)jgodeplianus. 



415. Zijgostephanium. 



416. CoronicUum. 

 Wl. A canthodesmia. 



418. Eucoronis. 



419. Pledocoronis. 



420. Podocoronis. 



IV. Subfamily 



Trissooyclida. 

 Eight large gates (four 



upper lateral and four 



lower basal). 



Four upper 



gates larger 



than the 



Two meridional rings 



(sagittal and frontal) 



and the horizontal , j. , 



1 1 . 1 i lour lower. 



basal nng complete. < 



All three complete 



rings perpendicular . i, . , , , 

 , ° ^ ^,, All eight gates 



to one another. c ^ ■ i 



ot equal size. 



Gates simple, . 421. Tristephanium. 



Gates partly lat- 

 ticed. 



422. Trkijdidium. 



Gates simple, . 423. Trissodrais. 



Gates partly lat- 

 ticed, 



424. Trissocydux 



Subfamily 1. Zygostephanida, Haeckel, 1881, Prodromus, p. 446. 



Definition. — C o r o n i d a with four large lateral gates, without basal gate. Skeleton 

 composed of two complete vertical rings, perpendicular one to another — the ]5rimary 

 sagittal and the secondary frontal ring. 



Genus 414. Zygostephanus,^ Haeckel, 1862, Monogr. d. Eadiol., p. 268. 



Definition. — C o r o n i d a with four large, simple, lateral gates, without basal gate 

 and lattice-work. Skeleton composed of two simple meridional rings, perpendicular to 

 one another. 



The genus Zygosteplianus, founded by me in 1862 for the Mediterranean Zygoste- 

 ■phanus mUlleri, is the simplest and most primitive of all the Coronida, and may there- 



' Zygostephanm = YdkeA ring ; ^vyou, aTi(ficiiios. 



