210 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Revision and described some of the growth-changes. It may be added here 

 that in half-grown specimens only five ambulacral plates, with five large penicil- 

 late tube-feet enter the subanal fasciole on each side, while in specimens 150 

 mm. long, there may be ten such plates, with nine big tube-feet, on each side. 

 Intermediate stages may be found on specimens of intermediate size. The 

 number of ambulacral plates may be different on the two sides in these 

 intermediate specimens. Owing to Bolau's (1874. Arch. f. Naturg., 40, 1, 

 p. 177) failure to give any data regarding the subanal plastron and fascioles, 

 I am unable to satisfy myself as to his proposed species Brissus sternaloides, 

 but suspect it is a growth-stage or an individual variant of the present species. 

 It may, however, be a true Brissus. 



The pedicellariae of this species show much diversity in specimens of differ- 

 ent size. In half-grown individuals the tridentate all have three valves, measur- 

 ing .25-.40 mm. in length, while in adults, these pedicellariae have two-six, 

 usually five valves which are from .35 to 1.50 mm. long. Bidentate pedicellariae 

 (PL 146, fig. 80) are not rare in a big specimen from Mauritius, but they are of 

 small size and resemble those of certain clypeastroids. In the large tridentate (or 

 quadri- and quinquidentate) , the valves are narrow, coarsely serrate or dentate 

 on the margin and more or less expanded at tip. The rostrate pedicellariae 

 are not distinctive but the blades are not expanded at the tip; in small indi- 

 viduals, the rostrate valves are .35-.55 mm. in length, while in adults, they 

 are .75-.85 mm. long. It is evident that in this species growth-changes in the 

 test are accompanied by growth-changes in the pedicellariae. 



Metalia spatagus. 



Echinus spatagus Linn6, 1758. Syst. Nat., ed. 10, p. 665. 

 Metalia maculosa A. Agassiz, 1872. Rev. Ech., pt. 1, p. 144. 

 Metalia spatagus Lov6n, 1887. Ech. Linn., p. 162. 



The geographical distribution of this species is remarkable for there seems 

 to be no doubt that it occurs at Panama and at Cape St. Lucas, Lower Cali- 

 fornia, as well as from Hawaii to Mauritius and from the Society Islands to 

 Sagami Bay, Japan. Pedicellariae are sometimes very rare and are seldom 

 abundant apparently, but specimens f"om different localities show much diversity 

 in this respect. As in stcrnalis, the larger the specimen, the larger the pedicel- 

 lariae. The tridentate always have three valves and only three: these, however, 

 range in Length from about .20 mm. to over a millimeter; the longer the valves 



