106 THE VOYAGE OF H.M.S. CHALLENGER. 
Genus 24. Orbicella, Dana. ; 
Orbicella, Dana, Zoophytes, p. 206. 
Heliastrea, Milne-Edwards and Haime, Cor., ii. p. 456, 
Be Duncan, Rev. Madrep., p. 104. 
Verrill* has pointed out that this name should be applied to this group rather than 
the later term Heliastrea of Milne-Edwards and Haime, which has been adopted by 
the generality of recent writers. 
Orbicella cavernosa (Esper). 
Madrepora cavernosa, Esper, Pflanz. Forts., p. 18, Madrep. pl. xxxvii. 
Orbicella argus, Dana, Zoophytes, p. 207. 
Heliastrea cavernosa, Milne-Edwards and Haime, Cor., ii. p. 463. 
From the accurate descriptions given by Dana and by Milne-Edwards and Haime of 
this common West Indian form, the specimens obtained off Barra Grande, Brazil, differ 
but slightly in having the surface of the intercalicinal spaces vesiculate, causing 
the union of the coste of adjoining calicles with one another to be indistinct, and 
also in having the septa more uniformly thickened throughout. It was obtained from a 
depth of 30 fathoms, and tends to prove that species of Coral, which are reef-building 
forms, live at much greater depths than. is usually believed. The rounded masses, as 
stated by Professor Moseley in his journal, were about 2 feet in diameter at the flat 
base, and were extremely and regularly convex above. When broken open, these 
masses were found to be bored by Lithodomus dactylus, but the molluses were dead, 
apparently shut in by the rapid growth of the Coral. 
Locality.—Barra Grande, Brazil, 30 fathoms. 
Genus 25. Cyphastrea, Milne-Edwards and Haime. 
Cyphastraa et Solenastrea, Milne-Edwards and Haime, Cor., ii. pp. 484, 495. 
Following Klunzinger,’ I have united the genera Solenastrea and Cyphastrea 
under the latter name, which was first defined by Milne-Edwards and Haime, and 
should therefore be retained. The extreme forms of the genus present very striking 
differences, and would certainly warrant generic separation but for the clearly intermediate 
nature of many other species. 
Four species were obtained. 
1. Cyphastrea plecades (Ellis and Solander). 
Madrepora pleiades, Ellis and Solander, Zoophytes, p. 169, pl. liii. figs. 7, 8. 
Astrea pleiades, Dana, Zoophytes, p. 213, pl. x. fig. 5. 
A dead and worn specimen occurs in the collection. The size of the cells is rather 
variable, being often only 2 mm., especially towards the basal part of the colony. The 
1 Dana, Coral and Coral Islands, p. 336. 2 Cor. roth. Meer., iii. p. 50. 
