THE 
VOYAGE OF H.M.S. CHALLENGER. 
ZOOLOGY. 
REPORT on certain Hyprorp, Atcyonarran, and Maprerorartan Corats pro- 
cured during the Voyage of H.M.S. Challenger, in the Years 1873-1876. 
By H. N. Mosetey, M.A., F.R.S., Fellow of Exeter College, Oxford, late 
Member of the Civilian Scientific Staff of the Challenger Expedition. 
GENERAL INTRODUCTION. 
Ar the time when the Challenger Expedition set sail, very few investigations concerning 
the anatomy of the soft tissues of stony corals had been made for a considerable number 
of years. A large number of naturalists had failed to accept as conclusive the late 
Professor Agassiz’s results as to the hydroid nature of the MILLeporip#; the Sryas- 
TERID& were universally considered to belong to the MapreporartiA, although Gray had 
formed them into a special family, and Pourtalés and Verrill had recognised some of the 
remarkable peculiarities of these corals. The presence of “tabule” in Heliopora had 
led to the association of that form with Millepora, and no one suspected that it was an 
Aleyonarian allied to Coralliwm, Tubipora, and Aleyonium. 
When I undertook the investigation of the deep-sea MADREPORARIA dredged during 
the voyage, I naturally became anxious to examine the structure of Millepora, and 
early in the expedition attempted to make out the anatomy of Mullepora alcicornis at 
Bermuda, but without much success, the problem proving too difficult. I did not succeed 
with Millepora until near the end of the voyage. The discovery which I made at the 
Philippine Islands, that Heliopora is an Alcyonarian, led me to examine the structure of 
all corals which were not most evidently Madreporarian, and hence I studied Stylaster, 
". (Z00L. CHALL. EXP.—PART vil.—1880.) Gl 
