280 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



The disk is 7 mm. in diameter. The mouth is interradial and lies rather centrally. 

 Scattered over the disk are calcareous concretions, which are especially numerous 

 in the anal area. 



According to Hartlaub the color in alcohol is usually pure white, more rarely 

 (Blake station 246) brownish white, sometimes (Blake station 203) with 2 dark 

 longitudinal lines on the arms. 



Hartlaub remarked that the very youngest specimens are determinable by the 

 form of the cirrus segments and the well-developed comb on P b while, as is shown by 

 a very small specimen from Blake station 1 27, the carination of the basal segments of 

 the pinnules is less diagnostic. This very young individual has long brachials which 

 are strongly constricted centrally. 



Two others, without locality, which are just as young, have the carination of the 

 basal segments developed on PI, or even on PI and P 2 . Another young individual, 

 also without locality, is remarkable in having the brachials with a granulated surface, 

 an ornamentation which was not observed by Hartlaub in any other West Indian 

 comasterid. 



Hartlaub says that intermediates occur between carinata and most of the other 

 varieties of Actinometra echinoptera, with the exception of var. valida (Comactinia 

 echinoptera) and var. alata (Neocomatella alata). Some of these he described under 

 the name of var. meridionalis-carinata, which includes specimens of both Comactinia 

 echinoptera and Leptonemaster venustus. 



He considered Actinometra echinoptera var. carinata as especially close to 

 Actinometra echinoptera var. rubiginosa (Nemaster rubiginosa). 



A specimen from Blake station 156 with strongly keeled lower pinnules, according 

 to Hartlaub, shows the yellowish speckling of the arms, especially on the syzygial pairs, 

 which is present in Actinometra echinoptera var. pulchella (Neocomatella pulchella) . 



Significant also, according to Hartlaub, are those intermediates between this 

 form and Actinometra echinoptera var. discoidea (Nemaster discoidea). They show 

 the remarkable features of the pinnule segments of discoidea, without, however, 

 possessing the interradial plating of the disk which especially distinguishes the 

 varieties discoidea (Nemaster discoidea) and lineata (Nemaster rubiginosa). 



One of the specimens from Blake station 32 carries several large stalked barnacles 

 of the genus Scalpellum on the cirri. 



The specimen in the Museum of Comparative Zoology from the University of 

 Iowa's Bahamas Expedition station 7, determined by Dr. H. L. Clark as Comactinia 

 echinoptera, is in reality this species; it has the arms about 70 mm. long. 



Eight specimens from Blake station 155 have the arms up to 60 mm. in length. 



Hartlaub noted that the specimens from Blake station 203 have especially 

 rough arms and pinnules, as a result of sharper and more spinous distal edges to the 

 brachials and a development of small spines on the edges of the pinnule segments. 

 In one of these specimens the mouth, which is interradial, is almost central. 



One of the specimens recorded by Hartlaub as Actinometra echinoptera var. 

 meridionalis from Barbados is in reality this species, as is shown by his figure. He 

 mentions this specimen as typical of those showing an approach, through an espe- 

 cially slender form and somewhat elongated brachials with smooth arm bases, to 

 var. carinata. 



