ECHINOIDEA. II. 



149 



The sphaeridise, on the contrary, are very early developed, viz. the first 5 of them. Already in the 

 youngest specimens of only O'5' nro , where remnants of the larval skeleton are still quite distinct within 

 the abactinal skeleton, they have appeared. 



In the smallest specimens, of only O'5 mm , there are already bottom-particles in the intestine, 

 which shows that they begin the diet of the grown specimens as soon as their pelagic life has 

 come to end. 



Very nearly related to Ech. cordatum is Ech. australe Gray, so nearly, indeed, that it may be 

 doubted, whether they are not identical. Agassiz, though recognizing its close affinity to Ech. cor- 

 datum, ( Revision of Echini p. 580) states that specimens of this species are readily distinguished 



from the Atlantic E. cordatum Seen in profile the test rises somewhat more gradually from the 



anterior extremity towards the apical system; the abactinal pole is more central, and the anal system 

 is elliptical, slightly transverse, instead of being longitudinal, as iu E. cordatum. The bare abac- 

 tinal posterior ambulacral areas extend to the ambitus, remaining of the same width, instead of be- 

 coming narrow as in E. cordatum; the pores of the poriferous zones are more distant than in E. cor- 

 datum*. In the Challenger-Echinoidea (p. 174) these characters are stated to be quite constant in 

 the specimens examined, but Professor Agassiz adds that they seem very slight ground for main- 

 taining the specific distinctness of the Pacific and the Atlantic representatives of the genus, and I 

 should expect that additional material will prove this species to be identical with the European species*. 

 This suggestion is probably quite correct I have examined several specimens from Australia, Japan 

 and (one) from the Cape, and I find them to agree with cordatum in all essential features : the labrum, 

 the number of pores included within the subanal fascicle, the shape of the anal area (as shown above 

 it is of rather variable form in cordatum, so that no reliable difference is to be found herein), the form 

 and size of the petals as well as the number of their pores ( the difference in the posterior petals 

 said to exist by Agassiz I am quite unable to see ), the arrangement of the pores of the odd 

 anterior ambulacrum in double series, the position of the apical system ( I do not find it more cen- 

 tral in australe than in cordatum ), the larger tubercles in the anterior interambulacra in short, I 

 find them to agree completely in all essential features, so that they are, indeed, contrary to the origi- 

 nal statement of Agassiz, extremely difficult to distinguish. To be sure, I find the Ech. australe 

 somewhat lower at the anterior end, thus rising somewhat more gradually from the anterior extremity 

 towards the apical system , and perhaps also the pores of the anterior ambulacrum do not become 

 arranged in double series so early as in cordatum. 1 These, however, are so inconsiderable differences 

 that I doubt, whether it would be possible to distinguish with certainty tests of the two species, if 

 they were put together and the localities of the specimens not marked. In the pedicellariae I do not 

 find any reliable differences but it is to be remarked that I have not found any globiferous pedi- 

 cellarise in australe; upon the whole pedicellarise seem to be very scarce in this form. Regarding the 

 spicules I find the large rods below the terminal disk to be generally somewhat smaller than in cor- 

 datum; on the other hand the spicules of the frontal tubefeet are generally somewhat larger and 



1 Hutton (Catalogue of the Echinodermata of New Zealand. 1872. p. 14) says of Atnphidetus sealandicus (= Ech. 

 australe) that it has four genital pores on each side; this is, of course, a mistake, caused by the ocular pores having been 

 taken to be genital pores. 



