ECHINOCARDIUM DUBIUM. 265 



Echinocardium mortenseni. 



Echinocardium intermedium Mortensen, 1907. Inqolf Ech., pt. 2, p. 143 (preoccupied). 

 Echinocardium mortenseni Thie>y, 1909. Rev. Crit. Pal., 13, p. 137. 



This interesting species, long confused with either flavescens or pennatifidum, 

 is known as yet only from the Mediterranean Sea, where it occurs at depths of 

 8-23 fms. 



Echinocardium dubium. 



A. Agassiz and Clark, 1907. Bull. M. C. Z., 51, p. 134. 



Plate 150, figs. IS. 



Length 33 mm.; width, 30 mm.; height (half-way between apical system 

 and posterior end) 20.5 mm.; height in front of apical system, 18 mm. The 

 apical system is somewhat depressed as in capense. The form of the test as seen 

 from above, the character of the tuberculation, the shape and size of the internal 

 fasciole and the structure of ambulacra III are better shown by the figure (PL 

 150, fig. 1) than by description. The shape of the test as seen from the rear, 

 the form and size of periproct and of subanal plastron, the composition of the 

 latter, and the size and form of the subanal and anal fascioles are equally com- 

 prehensible from fig. 2. The petals, however, show much better in the speci- 

 men than in the figure; the anterior petals are slightly depressed, especially 

 proximally, about 11 mm. long, with 9 or 10 pore-pairs in the posterior series; 

 the posterior petals are equally depressed, less than 11 mm. long, with 8 or 9 

 pore-pairs in the posterior (inner) series. The peristome (PL 150, fig. 3) is 

 twice as wide as long and the labrum is notable for extending backward far 

 enough to be in broad contact on each side with ambulacral plate 2. The color 

 of the larger specimen is yellow-brown; the smaller one is much paler. 



The secondary spines of the dorsal surface are 2-3 mm. long while the 

 primaries there are fully twice as large. On the oral surface, the primaries are 

 6-10 mm. in length. The primaries of the sternum are decidedly curved and 

 markedly spatulate at tip; the widening is gradual, however, and occupies the 

 terminal half of the spines or a little less. Very few pedicellariae were found, 

 no doubt partly because the specimen is in poor condition. A triphyllous, with 

 valves about .07 mm. long, resembles the same pedicellariae in capense. The 

 small tridentate (or rostrate) have valves .15-.25 mm. and resemble the corre- 

 sponding form in cordatum (see Mortensen's ; 1907. Ingolf Ech., pt. 2, pi. 17, 

 fig. 21). 



