416 BULLETIN" 103, UNITED STATES NATIONAL MUSEUM. 



Genus GONIASTREA Milne Edwards and Haime. 



1848. Goniastrea Milne Edwards and Haime, Comptes Rend., vol. 27, p. 495, 

 Type-species. — Astrea retiformis Lamarck. 



GONIASTREA CANALIS, new species. 



Plate 91, fig. 4. 



Corallum massive, rounded or flattened on the upper surface, 

 forms masses 15 cm. or more in diameter. 



Calices joined directly by their walls, shallow, polygonal deformed; 

 lesser diameter of adult calices about 3.5 mm., greater diameter from 

 3.5 mm. up to 5.5 mm. 



Septa about 42, in a calice 3.5 mm. wide by 4 mm. long; of these 

 11 extend to the columella, and there are about 21 small (rather 

 rudimentary) septa. The inner ends of the smallest septa are usually 

 free; but the septa of the intermediate size fuse to the sides of the 

 members of lower cycles, and in places a small septum fuses to the 

 side of a member of a lower cycle. As is normally the case in corals 

 reproducing by fission, the septal arrangement is not definite. About 

 10 septa, alternately larger and smaller, were counted in a space of 

 2.25 mm. along the wall. At the wall the interseptal spaces are 

 about as wide as the thickness of the larger septa. Septal faces 

 with some granulations. Septal margins too badly damaged to 

 permit a study of their characters. 



Columella false, fairly well developed, formed by the fusion of the 

 inner end of the long septa. 



Asexual reproduction by fission, either equal or unequal, equal 

 fission seems more common. 



Locality and geologic occurrence. — Canal Zone, station 6016, quarry, 

 Empire, in the Emperador limestone collected by T. W. Vaughan 

 and D. F. MacDonald. 



Type.— No. 324996 U.S.N.M. 



Of the species of Goniastrea previously described from the American 

 Tertiaries, G. variabilis Duncan^ from the upper Eocene St. Bar- 

 tholomew limestone, French West Indies, has larger calices, about 5 

 mm, wide, and as it has about 40 septa to a calice, the septa in it are 

 less crowded than in G. canalis. I collected in the Oligocene of 

 Antigua, in the Antigua formation, a species of Goniastrea, that is 

 evidently the same as StepJianocoenia reussi Duncan,^ This differs from 

 G. canalis only by the absence of rudimentary septa between the 

 larger septa. The two forms, although closely related, seem to 

 represent distinct species. 



1 Geol. Soc. London Quart. Joum., vol. 29, p. 557, pi. 21, fig. 11, 1873. 



2 Idem, vol. 24, p. 19, pi. 2, fig. 1, 1867. I have excellent photographs of Duncan's type, which is No. 

 5011, Brit. Mus. Nat. Hist. 



