152 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Palaeotropus josephinae. 



Loven, 1872. Of v. Vet. Akad. Forh. f. 1871, no. 8, p. 21. 



Plate 145, figs. 27-3^. 



Although the amount of material in the M. C. Z. is not very great it is suffi- 

 cient to show that Mr. Agassiz's Palaeobrissus hilgardi is the adult of this species, 

 which was described from immature specimens, only 11-12 mm. long. Unfor- 

 tunately I have not seen Loven's type but I do not think Air. Agassiz made a 

 mistake in considering the small specimens of Palaeotropus taken by the Blake, 

 identical with Loven's species. One of these now before me is less than 17 mm. 

 long, is 10 mm. high and shows 2 distinct genital pores and a very distinct sub- 

 anal fasciole. The height is a little more than .60 of the length. In Loven's 

 much smaller specimen the height was .61 of the length. A specimen 23 mm. 

 long is no higher than the smaller one (10 mm.) and hence the height is only 

 .44 of the length, but the subanal fasciole is very distinct and there are only 

 two genital pores. A third specimen, 28 mm. long is 12 mm. high (height = 

 .43 of length) has the subanal fasciole evident but not complete and a third 

 genital pore is present, though very small; it lies in genital 3. A fourth specimen, 

 one of the types of Palaeobrissus hilgardi, is 42 mm. long and 16 mm. high 

 (height = .38 of length); there is no indication of a subanal fasciole but there 

 are only two genital pores of normal size, the one in genital 3 being small and 

 functionless. Finally the specimen figured in the Blake Report (PI. 24, fig. 15) 

 is 47 mm. long, 15 mm. high (height = .32 length), shows no trace of a subanal 

 fasciole and has 4 genital pores, though the two anterior are decidedly smaller. 

 I think no one can examine this series of five specimens without being satisfied 

 that they represent a single species, and that it is exceedingly difficult, if not 

 impossible, to doubt that they are all josephinae. It is evident that the number 

 of genital pores is a matter of age, as is also the condition of the fasciole ami 

 the flatness of the test. I believe too that the arrangement of the dorsal plates 

 in the ambulacra (I and V especially) depends largely on age but is also subject 

 to individual diversity; it seems therefore conclusive that not only is Palaeo- 

 brissus Jiilij<inli a synonym of Palaeotropus josepkhuu but the same is true oi 

 Koehler's Palaeotropus hirondeUei. Koehler apparently overlooked the facts 

 thai the Azores are the type locality (or josephinae, and that the figures in the 

 Blake Report are from much larger specimens. Comparison of the figures 

 here given of the pedicellariae of West Indian specimens y" hilgardi") with 



