246 HAWAIIAN AND OTHER PACIFIC ECHINI. 



in Berlin and states that it is certainly not a Spatangus, but he does not commit 

 himself as to the genus to which it does belong. I am placing it in Gonimaretia 

 on the strength of Studer's figures. 



Maretia. 



Gray, 1855. Cat. Rec. Ech. Brit. Mus., p. 48. 

 Type, Spatangus planulatus Lamarck = Spatangus ovatus Leske, 1778. Add. ad Klein, p. 188. 



Aside from the type species, which seems to be common, the members of 

 this genus are little known, three of the other four species, being based on unique 

 specimens. The appearance of the ventral surface is very characteristic for 

 only Lovenia and Pseudolovenia can rival Maretia in the smallness of the tubercu- 

 lated part of the sternum, and those genera are easily distinguished by the 

 characters of the dorsal surface. Young individuals of Gymnopatagus in which 

 the peripetalous fasciole is very slightly developed may be mistaken for Maretia, 

 unless attention is directed to the labrum and sternum. The pedicellariae of 

 Maretia are not at all distinctive, so far as they are known; globiferous have 

 been found only in one species and ophicephalous in three, and there is no sharp 

 line between the rostrate and the tridentate in any species. 



Key to the Species of Maretia. 



Height of test less than half its length. 



Test-width more than .75 of length ; width of bare ventral area .40 of test-width or 

 more. 



No large primary tubercles in interambulacrum 5 dorsally. 



3 or 4 very large and deeply sunken primary tubercles in each of interam- 



bulacra 1, 2, 3 and 4 dorsally tuberculata. 



Primary tubercles in interambulacra 1, 2, 3 and 4 dorsally more numerous 



and much less conspicuous ovata. 



Many large primary tubercles in interambulacrum 5 dorsally peloria. 



Test-width scarcely .70 of length; width of bare ventral area about .33 of test- 

 width; test nearly uniformly covered with primary tubercles, no distinctly 



larger ones on dorsal surface eliiptica. 



Height of test more than half its length elevata. 



Maretia tuberculata. 



A. Agassiz and Clark, 1907. Bull. M. C. Z., 61, p. 134. 



Plate 1G0, figs. 5-7. 



Length 26 mm.; width, 22 mm.; height 12 mm. The form of the test, 

 the tuberculatum, and the extensively bare lower surface are all brought out well 



