332 HAWAIIAN AND OTHER PACIFIC ECHINI. 



there are two (or often only one) , and one (or more) of these secondaries is almost, 

 if not quite, as large as the primary. On each of these plates there are also 

 15-20 miliaries, of diverse sizes but all small. On each ambulacra! plate, there 

 is a primary tubercle close to the poriferous area and on the inner half of the 

 plate, there may be a second tubercle nearly as large. These inner tubercles 

 are of somewhat variable size and are altogether wanting on many plates. Be- 

 sides the miliaries in the poriferous area, already described, each plate carries 

 five or six more on its inner half, irregularly scattered but chiefly near the margins. 

 The areola of the primary tubercle occupies practically the whole height of the 

 plate, so that this series of tubercles bordering the poriferous area is very similar 

 to that of pachistus. 



The color of the test is grayish olive, becoming lighter actinally so that around 

 the actinostome it is nearly cream color. The poriferous areas are distinctly 

 lighter than the spaces between them. The larger tubercles are all white. Under 

 a lens, the coronal plates at least on the inner half are seen to be variegated with 

 a lighter shade, and in the median interambulacral areas these lighter lines tend 

 to form figures similar to those seen in formosus. The medial vertical suture 

 in both areas is indicated by a lighter line and the pits at the angles of the plates, 

 along this line, though very small, are still visible. 



This specimen was received into the M. C. Z. collection from Louis Agassiz, 

 in 1859. It bore no other label than "Australia," but was marked by A. Agassiz 

 " Nov. gen." No description of it has ever been published, as it has been hoped 

 that additional specimens might come into the collection. The hope has been 

 in vain however and attention is now called to this noteworthy species. While 

 it appears to be allied to formosus, as nearly as to any species of the genus, the 

 appearance of the ambulacra, when the specimens are placed side by side, is 

 strikingly different in the two. 



HOLOPNEUSTES. 



Agassiz and Desor, 1846. Ann. Sci. Nat., (3), VI, p. 364. 

 Type-species, Holopneustes porosissimus Agassiz and Desor, 1846, 1. c. 



There can be no question that if the law of priority is to be rigidly enforced, 

 this genus is without a name while the equally well-known Mespilia becomes 

 Holopneustes. To prevent such a disaster it is preferable to ignore the first 

 suggestion of Holopneustes by Agassiz in 1841, when he mistook one of Leske's 

 species and selected it as the type, and date the genus from the time of its first 



