history'. 



133 



forms a disk, distinct and flat, to which are annexed the rays, more or less elongated, 

 simple, or ramified, and without grooves at their under surface. 



1. Ophiura, Lam., Ag. = (Sect. A, De Blainville). — Disk much depressed; rays simple, 

 squamous ; spines very short, embracing the lateral plate. 



Types. — Ophiura texturata, Lam., 0. lacertosa, Lam. 



2. Ophiocoma, Ag., = Ophiura, De Blainville (Sect. B). — This genus differs from the 

 preceding by the long moveable spines which arm the rays. PI. XIII, fig. 4. 



3. Ophiurella, Ag. — Disk indistinct. All the species are fossil. 



0. carinata, Ag. {Ophiura carinata, Miinst.), Ophiura Egertoni, Ag. {Ophiura Egertoni, 

 Brod.), PI. XVII, fig. 4. 



4. AcROURA, Ag. — This genus approaches much to the Ophiura properly so called, 

 but it differs in this, that the small scales placed on the sides of the rays replace the 

 spines. The rays themselves are very slender. One species fossil. 



A.prisca, Ag. {Ophiura prisca, Miinst.) PI. XIV, fig. 5. 



5. AspiDURA, Ag. — A star of ten plates covers the superior surface of the disk, whilst 

 the rays, large in proportion, are surrounded with imbricated scales. One species fossil. 



A. loricata, k^. {Ophiura loricata, Goldf) PI. XIV, fig. 6. 



6. Tricaster, Ag. ; EuRYALE, Auct. — Rays bifurcate at their extremity. 

 T. palmifer, Ag. {Euryale palmifera, Lamk.) 



7. Euryale, Lamk. ; Astrophyton, Linck ; Gorgonocephalus, Leach. ; — Disk 

 pentagonal ; rays branched from the base. 



E. verrucosa, Lara., E. costata. Lam., E. muricata, Lam. 



Miiller and Troschel,^ in 1840, published their first memoir on the classification of the 

 Asteriadse, in which they grouped the living Ophiurse into five genera: — 1, Ophio- 

 lepis ; 2, Ophiocoma; 3, Ophiothrix ; 4, Ophioderma ; and 5, Ophionyx ; comprising 

 twenty -nine species. The same year they added three new genera : — 6, Ophiopolis ; 7, 

 Ophiomyxa ; 8, Ophiocnemis. In 1 842 the ' System der Asteriden, by the same authors, 

 appeared, in which three new genera — 9, Ophiarachna ; 10, Ophiacantha ; and 11, 

 Ophiomastix, were added. The Euryalid^ comprised three genera — Asteronyx, Trichaster, 

 and Astrophyton, making in all fourteen genera, and comprising eighty-three species of 

 living Ophiuroidea, besides fourteen extinct species distributed in seven genera. 



In 1841 Professor Edward Eorbes, in his 'History of British Star-fishes,' described 

 thirteen species of OpHiuRiDiE as Spinigrade Echinodermata, which he distributed 

 in the genera Ophiura, Ophiocoma, Astrophyton, and in 1843,^ in a memoir com- 

 municated to the Linnean Society, he proposed several new genera — 1st, Pectinura 

 which nearly corresponds to the genus Ophiarachna; 2, Amphiura, which resembles 

 Ophiolepis ; and 3, Ophiopsila, which comes near Ophiothrix. He retained the name 



1 ' Archiv fiir Naturgeschichte,' p. 326. 



2 Edward Forbes, 'History of British Star-fishes.' Van Vorst, 1841. 

 ^ ' Transactions of the Linnean Society,' London, vol. xix, p. 144. 



