90 Howe : Phycological studies 



lime between the rays, the lime-coating often flaking off at matu- 

 rity: disc solitary, nearly flat, 1-2.5 mm. in diameter; sporangia 

 (rays) 6-17 (mostly 11-15), obovoid-clavate to clavate-subfusi- 

 form, 2-3^ times as long as greatest width (which is at two 

 thirds or three fourths of their length), bluntly subcorneal, obtusely 

 taper-pointed, or occasionally rounded obtuse, rather easily sepa- 

 rable and often more or less free on drying, mostly free in mature 

 specimens after decalcification ; coronal processes very small, 

 short-cylindrical, slightly enlarged at the top and appearing oval 

 or orbicular in surface view, 22-35 /^ in greatest diameter, each 

 bearing 2 (rarely 3) hairs, hair-rudiments, or hair-scars ; hypopeltal 

 processes wanting: aplanospores 15-60 in a sporangium, globose 

 or ellipsoid, 68-82 jjl in greatest diameter: stipe occasionally cor- 

 rugated and enlarged in the upper part, 0.1-0.2 mm, in maximum 

 diameter, [Plate 6, figures 13-15 ; plate 7, figures 1-4, 



On a reef, near low-water mark, with Neomeris anmilata and 

 Acetabulum polyphysoides^ Montego Bay, Jamaica, Hozve ^o2ga 

 (type), January 19, 1907; Mariguana, Bahamas, Howe S453 > 

 Castle Island, Bahamas, Hoiue ^yjib. 



Acetabulum pusillum differs from A, polyphysoides^ with which 

 it is sometimes associated, in its smaller size, in being strongly 

 calcified throughout, in the character of the coronal processes, 

 which are only 22-35/^ instead of 75-150^ in diameter and bear 

 only 2 (rarely 3) instead of 5-13 hairs, and in the smaller aplano- 

 spores, which are 68-82 // instead of 88-190/^ in diameter. It is 

 one of the most minute of the species thus far described in the 

 genus, the average diameter of the disc being about 1.6 mm. 



The nearest relatives of Acetabulum pusillum are apparently 

 two East Indian species, Acetabularia exigiia Solms * and A. 



of botanical nomenclature would prevent the adoption di Acetabulum, As a matter of 

 fact, the generic name in its original Tournefortian form was used in Boehmer's edition 

 of Ludwig's Definitiones Generum Plantarum (p. 504) in 1760, Tournefort being there 

 cited, as he was cited also by Linnaeus two years earlier, in establishing the binomial 

 Mad^-epora Acetabtdum (Syst. Nat. 793. 1758), so the name is technically free from 

 whatever opprobrium there may be in prelinnaeanism. The generic name Acetabulum 

 was used also by Lamarck in 1S16 (Hist. Nat. Anim. sans Verteb 2 : 149), though 

 this fact has no bearing on the priority question, as it was four years later than Lamou- 

 roux's establishment of Acetabularia (Nouv. Bull. Sci, Soc. Philom. 3: 185. 1812). 

 However, Olivia (Bertol. Rar. PI. Ital. Dec. 3 : I17. 1810), to which no valid ex- 

 ception can be taken, ant.edates Acetabularia and must be preferred to it under any en- 

 forcement of priority principles, unless a comparatively modern date betaken as a start- 

 ing point. Under the circumstances, we prefer the original Acetabulum^ which has a 

 clear post-1753 claim upon our favor. 



*Trans. Linn. Soc. Bot. II. 5: 2%,fL 2./, /, ^, 1895. 



