TERTIARY CALCAREOUS ALG^3. 13 



than high; tetrasporangial conceptacles numerous, becoming embedded, 

 oblong or elliptic-oblong in radio-vertical section, 380 to 770 M in maximum 

 width, 122 to 168 /* in height; roof of conceptacle flat or very slightly convex, 

 its cells 6 to 10 M (rarely 13 n) high, only slightly higher than broad. 



Hodges Bluff, lower bed (Oligocene, middle part of Antigua forma- 

 tion), Antigua, West Indies, T. W. Vaughan, No. 6862, 1 February 6, 

 1914. 



Lithothamnium concretum may deserve comparison with Lithotham- 

 nium suganum Rothpl., 2 from the Tertiary ("Scio-Schichten") of Val 

 Sugana, near Borgo in the Austrian Tyrol, but its perithallic cells 

 appear to be often larger (8 to 15 ju by 6 to 12 ju as compared with 9 

 to 12 /* by 7 to 9 ju) and its conceptacles also are much larger (380 to 

 770 M by 122 to 168 ju vs. 250 M by 100 /*). We have seen no pub- 

 lished figure or description of external form of L. suganum. Possibly 

 Lithothamnium torulosum Giimbel 3 is a nearer relative. This was first 

 found near Traunstein, in Bavaria, and was originally attributed to 

 the Oligocene, but Rothpletz 4 reports it from other localities in Europe 

 and thinks it belongs primarily to the Eocene. This forms rounded, 

 slightly lobed or warted masses (specimen figured is about 3 cm. by 

 1.5 cm., with elevations about 5 mm. in diameter). Giimbel gives cell 

 measurements as 8 /* by 6 ju, but Rothpletz makes the perithallic cells 



7 to 12 JJL by 7 to 9 JJL, from which it would appear that those of L. 

 concretum are a little larger. Giimbel did not describe or figure con- 

 ceptacles, but Rothpletz states that they are 400 /z by 150/z, which prob- 

 ably means that they are considerably smaller than in L. concretum. 



The plant is not closely related to any species of Lithothamnium 

 now living in the West Indian region, so far as is known to the writer. 

 In fact, it is not obvious with what living or recent species it may 

 best be compared. 



Since the above was written, the writer has received (May 1919) an 

 important paper by Madame Paul Lemoine on some fossil coralline 

 algae of Martinique, 5 the distribution of which paper has possibly been 

 somewhat delayed by war conditions. In this treatise several new 

 species are described, one of which, Lithothamnium lacroixi Lemoine, 

 based upon thin sections of pieces of calcareous rock thrown up by the 

 volcano Mount Pelee and of uncertain geologic age, evidently shows a 

 close affinity to L. concretum. It would, however, seem to be a more 

 crustaceous and less massive plant than L. concretum, with cells of the 



1 The sections shown in the micrographs, which may be considered the type material in a narrow 



sense, came from a fragment that has been labeled aa ; 6 is another alga, both from station 6862. 



2 Zeitschr. deutsch. Geol. Ges., vol. 43, 1891, p. 319, plate xvn, fig. 4. Compare also Capeder, G., 



Malpighia, vol. 14, 1900, pp. 176, 177, plate vi, fig. 3. 



8 Abhandl. mat.-phys. Cl. k. bayer. Akad. Wiss., vol. 11, abth. 1, 1871, p. 40, plate n, figs. 6a, 66. 



4 Zeitschr. deutsch. Geol. Ges., vol. 43, 1891, p. 318. 



5 Contribution a 1'etude des Corallinacees fossiles. Bull. Soc. Geol. de France, ser. 4, vol. 17 



1917, pp. 233-279. (Date of distribution, Dec. 1918; fide auct. in litt.) 



