688 Verrlll, Notes on Hadiata. 



is found to depend upon a very different internal structure, will 

 readily separate this species from E. occidentalis V. In the latter 

 the greatest elevation is in front of the center, and there is a regular 

 slope from thence to the broad, thin, posterior edge, and the sections 

 show that the wide space between the central cavity and the posterior 

 foramen is filled with a pretty firm, alveolar tissue, having compara- 

 tively small spaces, but in E. Californica the same region is much 

 less extensive (owing to the relatively larger centi*al cavity and jaws) 

 and is filled with a much less firm and more open tissue, with large 

 cavities. 



The difference is therefore analogous to that which separates E. 

 Michelini from E. eniarginata. 



Mellita longifissa Micheiin. 



Mellita longifissa Micheiin, Revue et Mag. Zool., 1858, No. 8, PI. 8, fig. 1; Verrlll, 

 Proc. Boston See. Nat Hist, xii, p. 383. 



This species is the Pacific analogue of M. pentapora of the Atlan' 

 tic coast. It is remarkable for the thinness or flatness of the outer 

 portion of its shell, the deeply sunken grooves of the lower surface, 

 and the length and narrowness of its five perforations, and especially 

 of the odd postei-ior one. The posterior side is somewhat truncate, but 

 a little rounded in the middle, and the posterior lateral perforations 

 are curved. The largest specimen from Gulf of California (Stearns) 

 is 3-8 inches in diameter; another is 2'95 wide, 2*70 long, -45 high; 

 the anterior pair of perforations "54 and "56 long ; the posterior pair 

 •b5 and "60 ; the posterior odd one -78 long ; -09 wide. 



La Paz, — Capt. Pedersen ; Gulf of California, — Robt. E. C. Stearns ; 

 Corinto, Nic, — J. A. McNiel. 



Clypeaster testudinarius nob. («"« Martens). 



Echinanthus testudinarius Gray, Proc. Zool. Soc. Lond., xix, 1851, p. 35; Cat. Ech. 



Brit. Mus, p. 6, PI 1, fig. 1, 1855. 

 Clypeaster speciosus Verrill, Am. Jour. Science, xlix, p. 95, 1870. 



Plate X, figures 7, 7'\ 

 Depressed, gradually rising toward the apex ; the lower side some- 

 times slightly concave from near the edge of the mouth, in other spe- 

 cimens flat, except close to the mouth, which is much sunken. Out- 

 line oblong-pentagonal, with rounded angles and slightly concave 

 sides. The anterior end slightly elongated. Interambulacral regions 

 decidedly concave between the ends of the ambulacral rosette ; the 

 ambulacral regions enclosed by the pores slightly raised, narrow, elon- 



