90 Dr. Th. Mortensen on some Echinothurids 



transverse row." This is not the case in tlie specimens before 

 me, anrl, to judge from the tigures given bj Yoshiwara, 

 it is doubtless simply due to the breaking of the plates in 

 liandling the specimens. A very startling statement is that 

 the teeth are keeled. This would be very curious and 

 unexpected, as all other Echinothurids have uiikeeled teeth. 

 The specimens before me, in fact, have unkeeled teeth, and 

 the statement of Yoshiwara is evidently wrong. 



1 must corroborate the statement that genital papilla3 occur 

 in this species, and it may be added that such structures 

 may also be found in C. hystrix, though generally little deve- 

 loped. The abactinal tube-feet are unequally developed, 

 those in the inner row being larger than the outer ones. 



4. PJwrmosoma verticillatum, sp. n. 

 (PI. IV. figs. 1, 2 ; PI. V. figs. 15-17.) 



This species, as regards general appearance, is very similar 

 to Ph. placenta. On the actinal side the large tubercles (and 

 areole.s) do not reach quite so close to the peristome as in 

 that species ; they are arranged in a broad band along the 

 outer edge of the actinal side, the inner part around the 

 peristome looking more naked, whereas in Ph. placenta the 

 large tubercles cover the whole actinal side from the outer 

 edge to the peristome. The marginal fringe of small spines 

 is well developed. The abactinal side of the test is almost 

 exactly as in placenta ; in the interambulacra the tubercles 

 are generally, but not always, arranged in an arc of three 

 on each of the outer plates ; on the uppermost plates the 

 number of tubercles is reduced to two or one, the arc thus 

 disappearing. This arrangement of the tubercles in a more 

 or less distinct arc may also occur in placenta, though seldom. 



The peristome is rather small, 19 mm. in a specimen of 

 63 mm. diameter; in a specimen of placenta of 66 mm. 

 diameter the peristome is 23 mm. Although there is some 

 variation in tiie size of the peristome in placenta^ it is upon 

 the whole undoubtedly somewhat larger in that species than 

 in verticillatum. The same fact holds good for the apical 

 system, and to a greater extent ; in the specimen 63 mm. in 

 duimeter of verticillatum the apical system is only 13 mm. in 

 diameter, whereas in the specimen of placenta 06 mm. in 

 diameter it is 22 mm. There is a distinct genital papilla, 

 winch may, however, also be the case \\\ placenta. 



The pedicellariai are quite like those of Ph. placenta ; the 

 tridentate pedicel lariae are of the short and broad form found 

 in specimens from Davis Strait and the Gulf of Mexico 



