BI 



HÄNG TILL K. SV. VET.-AKAU. HANDL. BAND 13. AFD. IV. N:0 5. 14o 



meter of 62,5 mm., and a height of 47 mm., or 0,7 6, and 10 

 or 10, .5 plates in each interradial series. The test has not as 

 miicli of the pentagoual form as that of the type, but more 

 than any otlier species. The ambulacnim III, at the height 

 of the 2h7 lias a l)readth of 7,2."i mm. or 0,24 of the inter- 

 radium, and the verv slightly concave areola measnres 2,7 5 

 mm. or 0,3 8 of the ambulaerum. The plates have, close to- 

 the marginal primary verrucula, a small secondary one placed 



1. 2. 



1. Echinus Oidaris L. 



Cidaiis baculosa 

 Lamck. 



adorally, followcd by auother sub-marginal still smaller to 

 which is added here and there a sub-sutural one, thus approxi- 

 matinsx the maturc specimen. The ambulacra are not fullv 

 as straight as in the type, but less flexuous than in anv other 

 speeies excepting perhaps the otlierwise very different C. tri- 

 buloides of tlie West Indies. 



The interradia project beyond the ambulacra though not 

 as much as in the Linnean type. The 5 lias a breadth of 30 

 ram., and its open middle area is 8,5 mm. or 0,2 8 3. It is not 

 as flat as in the E. Cidaris, tlic two halves faintly sloping 

 against the suture, the upper, younger plates more so than 

 the older plates below. In the ö a the plate 7 measures 16,5 

 mm. and tlie scrobicule 9,5 or 0,5 7 5, while in the Echinus 

 Cådaris the ö a 6 measuring 20,9 mm. has a scrobicule of 11,2 

 mm. or 0,5 3(1, which is in conformity with the rule observed 

 in the C. papillata, that the transverse inner diameter of the 

 scrobicule is longer relatively to the length of the plate in 

 younger than in mature spécimens. The two uppermost scro- 

 bicules, 9 and 10, are circular, in the E. Cidaris the 11 and 

 12. As in that species the scrobicules are shallow, the verru- 

 culse of the ring small, the four upper and tlie four lower very 

 minute, the lateral six or seven a little larger. A second 

 outer row is diminished, and then follow not verv distinct 



