202 Herbert L. Hawkins — Studies on the Echinoidea, etc. 



discussion of " Galerites" albogalerus which hear upon the subject. 

 *' The miliary tubercles of the dorsal plates bear very minute and short 

 tubercular smooth spines, each standing apart from its neighbours. 

 . . . [On the adoral surface] curious club-tipped pedicellaria-like 

 bodies occur among [the normal radioles], which may represent the 

 spines of the miliary tubercles described as occurring on the dorsal 

 surface. . . . The minute moniliform spines of G. albogalerus are 

 ts~3 of an inch in length and of equal diameter. Three were 

 measured, and all were as nearly as possible of the same size and 

 proportions. They were all perfectly smooth." On pi. viii, fig. 8 

 are given two " greatly magnified figures of the small tubercular 

 spines of the dorso-lateral plates". The spines figured are nipple- 

 shaped, with smooth domes and splaj'ed proximal margins. The 

 description is incorrect in one particular, for these prominences do 

 not occur on the miliary granules, nor yet on the secondary tubercles, 

 but in association with small pits which are not indicated on Forbes' 

 somewhat imaginative fig. 5. I am unable to confirm the presence 

 of the "pedicellaria-like" structures on the adoral surface, but they 

 may be attached by soft tissues only, and so only preserved when the 

 ordinary radioles are in place. Otherwise, save for the correction 

 made above, the description and figures seem thoroughly accurate, 

 though by no means complete. 



The study of such minute structures in a fossil is necessarily 

 attended with great difficulty, and the observations made in one case 

 need abundant and frequent comparison with separate investigations 

 on numerous specimens. Fortunately, the prominences are so thickly 

 scattered over the test, and examples of the species showing them in 

 place are so common, that sufficient material for confirmatory analysis 

 has been readily available. I have found that the most satisfactory 

 process for a study of the surface details of Co7iulus, and indeed of 

 most fossil irregular Echinoids, is to wash them over with Indian ink 

 much diluted with water. This reagent leaves a very fine black 

 deposit in all the small depressions of the test (such as plate-sutures 

 and podial pores) ; and, if the surplus be rubbed off with a damp 

 cloth before it has quite dried, only such depressions retain the 

 stain. A brush must not be used for the removal of the ink, for it 

 scours out the depressions irregularly, and produces disconcerting 

 results. It must be borne in mind that a specimen so treated cannot 

 be cleaned after the ink has once dried, so that valuable or borrowed 

 specimens must be examined in their natural state. 



PI. XIII, Fig. 8, shows the general appearance of a series of coronal 

 plates midway between the apical system and the ambitus in 

 a specimen of C. albogalerus from the base of the Uintacrinus sub- 

 zone of Shaw, near Newbury. All the projecting prominences have 

 been removed by rubbing with a stiff brush, but none of the 

 miliaries or tubercles have suffered in the process. The drawing 

 shows all the external ornament of the plates, correct in position and 

 proportions. To avoid perspective, the interambulacral plates have 

 been projected up to the plane of the ambulacrum which they flank, 

 the outlines having been traced from three separate photographs. 

 It will be seen that there are four types of ornament. The main 



