REPORT ON PHILIPPINE HYDROIDA 239 



The intrathecal ridge is short but strong. Nematophores, the supra- 

 calycine pair are large blunt thumblike in form with a terminal ori- 

 fice pointing upward and rising slightly above the hydrothecal rim. 

 Mesial nematophores enormous, almost equal to the hydrotheca in 

 diameter and reaching far beyond the hydrothecal margin. They 

 are free from the front of the hydrotheca above the intrathecal ridge 

 and sometimes this free portion equals the entire hydrotheca in 

 length. There is a small round opening from the nematophore into 

 the hydrotheca below the intrathecal ridge and another on the distal 

 end of the nematophore. The nematocysts borne by these mesial 

 nematophores are very long and narrow and a bundle of their very 

 complex threads is often seen projecting from the distal opening 

 of the nematophore. There is a very large nematophore resembling 

 the mesial ones near the base of each hydrocladium between the first 

 and second hydro thecae but projecting from the side of the hydrocla- 

 dium end at a right angle to the axis of the ordinary mesial nemato- 

 phore. Indeed, it looks like a misplaced mesial nematophore al- 

 though more nearly in the position of the supracalycine nemato- 

 phores. 



Gonosome. — Not present. 



Localities. — Dredging station 5139, vicinity of Jolo, Jolo Light, 

 6° 6' N., 121° 2' 30" E.; depth, 20 fathoms. Station 5165, Sulu 

 Archipelago, Tawi Tawi group, Observation Island, 4° 58' 20" 

 N., 119° 50' 30" E.; depth, 9 fathoms. 



Holotype.— Cat. No. 42187, U.S.N.M. 



The propriety of placing this extraordinary form in the genus 

 Halicornaria is doubtful. Indeed, in the absence of the gonosome it 

 is almost impossible to distinguish that genus from Lytocarpus. 



BIBLIOGRAPHY 



Aldee, Joshua. A Catalogue of the Zoophytes of Northumberland and Durham, 

 Transactions of the Tyneside Naturalists' Field Club, vol. 3, 1857. 



Allman, George J. Report on the Hydroida collected during the exploration of 

 the Gulf stream, Memoirs of the Museum of Comparative Zoology at Harvard 

 College, vol. 5, No. 2, 1877. 



Report on the Hydroida dredged by H. M. S. Challenger, pt. 1, 



1883, pt. 2, 1888. 



Bale, William M. Journal Microscopic Society Victoria, 1881. 



Catalogue of Australian Hydroid Zoophytes, 1884. 



The Genera of the Plumularidae, etc., 1887. 



Some New and Rare Hydroida in the Australian Museum Collec- 

 tion, Proceedings of the Linnean Society, New South Wales, vol. 3, ser. 2, 

 1888. 



Report on the Hydroids collected in the Great Australian Bight, 



1914. 

 Transactions and Proceedings of Royal Society of Victoria, 1914, 



new ser., vol. 27. 



