496 Verrill, JVotes on RacUata. 



Mammillifera Danse Verriii. 



Zoantha DanailieQonte, Pri>c. Philad. Acad. Nat. Science, v, p. 320, 1851. 

 Zoanthus {Mammillifera) Dance Verrill, Proc. Boston Soc. Nat. Hist., x, p. 329, 1866. 



The original description is as follows : " pallide pnrpurascens, ten- 

 taculis brevissimis, crassitie non longioribus, disco viridi, extrorsum 

 purpurascente, ore parvo purpureo-marginato, tentaciilis externis basi 

 pallidis. Diam. disci "25 unc." 



"Remarkable for the shortness of the tentacula, which, when fully 

 extended, are scarcely longer than the diameter of their base. The 

 disk is radiately rugose, brilliant green, margined both internally and 

 externally with purple. The root is broad, the animals closely asso- 

 ciated, capable of extending 1'25 inches." 



The specimens referred to this species form broad patches, covering 

 the su.rface of rocks, the basal expansion being mostly continuous, but 

 occasionally, in some parts, taking the form of broad irregular sto- 

 lons, rarely linear for a short distance. The basal membrane and sur- 

 faces of the polyps are smooth and soft, without any adhering sand. 

 The polyps in preserved specimens are closely arranged, but usually 

 not so crowded as to be in contact, and vary in height from '2 to '5 of 

 an inch ; diameter of mature polyps is usually about '2 of an inch. Col- 

 umn sub-cylindrical, with a rounded top when contracted, or low and 

 mammiliform. Tentacles, in specimens dissected, 46 to 54 in number, 

 in two regular rows, very short, thick, and obtuse, in the largest speci- 

 mens in two alternating rows of 27 each. Inside of the bases of the 

 inner tentacles, but alternating with them, are 27, small, oblong, tuber- 

 cles, which are, therefore, opposite the outer tentacles. Disk strongly 

 radiated. 



In the interior the lamellaj are arranged bilaterally, 21 broad ones 

 bearing the peculiar " arcuated organs " (branchiae ?) below the stom 

 ach ; in the spaces between each pair of these there is usually one nar 

 row lamella, but in two adjacent spaces on one side there are three 

 intervening lamellse, and in two other spaces, placed symmetrically in 

 respect to the median plane, there are two small lamella?. This 

 arrangemant is, therefore, nearly the same as in 31. auricula, as fig- 

 ured by Lesueur.* It would appear, therefore, that the lamellae and 

 tentacles increase by pairs, introduced one on each side of the median 

 plane passing through the longer axis of the mouth and stomach, as 

 observed in Arachnactis by Mr. A. Agassiz.f 



* Journal Philadelphia Academy, i, PI. viii, fig. 3. 



\ Journal Boston Soc. Natural History, vol. vii, p. 525, 1863. 



