CLYPEASTER PROSTRATUS. 37 



is difficult to determine and it is only alter much deliberation that I have decided 

 to use the name first given by Leske and later used by Mr. Agassiz in the Revi- 

 sion. It seems to be true that in a general way Echinanthus humilis Leske is a 

 synonym of Echinus rosaceus Linn^ but as soon as Lamar('k in 1801 definitely 

 restricted rosaceus to the West Indian form with which that name has since 

 I)(>en associated, humilis was no longer synonymous with it except in small 

 ])art and hence it is permissible to use hxiviilis for one of the forms included by 

 Leske under that name. Certainly Loven seems to be wrong in attempting 

 to apply Linne's name rosaceus to this species, since Lamarck long ago restricted 

 it to the West Indian form, but he seems to be quite right in maintaining that 

 Lamarck's Scutella 'placunaria is not a Clypeaster at all and therefore the name 

 -placunarius cannot be correctly used for this species, even if we reject humilis. 

 Dr. Doderlein tells me, and I am cjuite ready to agree with him, that Pfeffer's 

 Alexandria magnifica, which has been a puzzle to systematists, is based on a 

 fine alcoholic specimen of this Clypeaster. 



The abactinal primary spines of this species tend to be small, rough, and 

 slightly enlarged near the tip; the miliaries are not peculiar. Pedicellariae 

 seem to be quite rare for on one specimen, one ophicephalous pedicellaria was 

 all I could find and there were no tridentate, while on another specimen, tri- 

 dentate were found but not an ophicephalous. The head of the ophicephalous 

 was about .40 nnn. long and the loops on the valves, particularly on the largest, 

 were remarkably big (PI. 123, fig. 23). The valves of the tridentate are about 

 .90 mm. long, narrow but broadly expanded at tip somewhat like fig. 2, PI. 124. 

 The known geographical range of humilis is from the Red Sea and Mauritius 

 to the East Indian Islands. 



Clypeaster prostratus. 



Scutella gibbosa Ravenel, 1S4.5. Proc. Acad. Nat. Sci. Philadelphia, 2, p. 253, non Risso, 1826, Hist. 



Nat., p. 284. 

 Clypeaster prostratus Ravenel, 1848. Ech. Rec. Foss. South CaroUna, p. 3. 

 Clypeaster subdepressus A. Agassiz, 1872. Rev. Ech., pt. 1, p. 101 (par.s) ; PI. xi°, figs. 1, 2. 



Examination of two fine specimens in the M. C. Z. collection, one from South 

 Carohna and one from Georgia, has satisfied me that this species is perfectly 

 distinct from the West Indian subdepressus. The form of the test and the 

 appearance of the petals are very characteristic features, well shown in Mr. 

 Agassiz's figures. The spines and pedicellariae are similar to those of subdepressus 

 except that the tridentate are the only pedicellariae found and their \-alves are 



