VAUGHAN : MADREPORARIA. 67 



somewhat less than 1 mm. to almost 2 ram. apart. From three to five tliin, mem- 

 braniform synapticula, formed by the basal fusion of opposed carinae, occur in each 

 interseptal loculus. 



The inner ends of the septa are united by a calcareous membrane, through which 

 small, thin, spinose, septal processes project. The diameter of the columella plat- 

 form is 6 mm. 



Localities: — (Trjpe) — Station 4721 between Galapagos and Barrett Ridge ; 

 depth 2,084 ftns. ; bottom, light brown Globigerina ooze, sponge, spicules, 

 diatoms, a few Radiolaria; thermometer failed to register on the bottom; 

 1 specimen. 



Station 4670 western edge of Milne Edwards Deep off Callao ; depth 3,209 

 fms. ; bottom, soft, light brown mud; temperature of the bottom, 35.4° ¥.; 

 3 specimens, partially decalcified, two were cleaned by boiling in a solution of 

 caustic potash, and were easily identifiable. 



A specimen of Bathyactis, which had been decalcified, was dredged at station 

 4732, between Barrett Ridge and Manga Reva, at a depth of 2,012 fms. This 

 specimen is not specifically identifiable, but probably belongs to B. marenzelleri. 

 Bottom, light gray, Globigerina ooze, sharks* teeth, and ear bones, manganese 

 nodules, very few diatoms and radiolaria, sponge spicules ; temperature of the 

 bottom, 34.8° F. 



Remarks : — This species according to Alcock's synopsis of the species of 

 Bathyactis ^ obtained by the " Siboga " is nearest to B. symmetrica (Pourtales), 

 as it possesses no pali and only four cycles of septa. But it differs markedly 

 from that species. The shape of the septa and the character of their margins 

 are entirely different — the great elevation of the septal margins and their pecu- 

 liar laceration are very striking. B. sibogae Alcock is similar to B. symmetrica, 

 diflFering by possessing five, instead of four, cycles of septa. B. Stephana 

 Alcock possesses elevated septal margins, but the base of the corallum is 

 concave and there are five cycles of septa. Alcock's figure ^ of the last named 

 species indicates that its septal margins are peripherally narrow or excavated, 

 and that they are elevated near the calicular fossa, the reverse of the condition 

 in B. marenzelleri. B. havmiiensis Vaughan has a general similarity in form, 

 but it possesses five cycles of septa, its septal margins are not so lacerate and 

 the carinae on the septal faces are much more crowded, and bear spinose granu- 

 lations. It therefore seems that B. marenzelleri is decidedly dififerent from any 

 other hitherto discovered species of the genus. 



Balanophyllia galapagensis, sp. nov. 



Plate 4, Figs. 3-3 b. 



Corallum elongate, slightly curved, with broadly elliptical transverse outline. 

 The lower end is broken and the calicular margin is somewhat, but not greatly, 

 damaged. The following are the measurements : length, 20.5 mm. ; lower end, 



1 Deep-Sea Madreporaria of the Siboga Exped., p. 37. 



2 Investigator Deep-Sea Madreporaria, plate 3, fig. 5a. 



