24 BULLETIN 115, UNITED STATES NATIONAL MUSEUM. 



Nevertheless they afterwards often stated as to a new species that 

 it " differs from all others in surface ornamentation and nmnber of 

 arms." Unless fairly definite stages of these surface modifications 

 can be correlated with some other character, I am unable to regard 

 them as of much practical value in the discrimination of species^ 

 (See further under D. incisus and D. asperatus.) 



So-called " azygous side." — This was Miller's term for what other 

 authors usually call the posterior, or anal, interradius. In this 

 genus that side is usually not differentiated in the dorsal cup by any 

 increase in the number of plates, but may be in some cases by the 

 greater size of corresponding plates. The first and second ranges of 

 interbrachials consist normally of one plate each, from which number 

 thqy rarely vary; slight differences occasionally occur in the third 

 range, but these are sporadic, not constant for the species, and may 

 be disregarded in the descriptions. 



Pinnule openings; ^'ovarian apertures" ; or ''pores." — Much has 

 been said in the specific descriptions about the openings through the 

 calyx wall which occur in varying numbers in the zone of the arm 

 bases. They have been called "ovarian apertures" by Miller and 

 Gurley, and "respiratory pores" by Wachsmuth and Springer. As 

 already stated, I have elsewhere'" shown by conclusive evidence 

 of specimens in which the parts are perfectly preserved that these 

 slit-like openings or pores, which occur also among the Batocrinidae, 

 Platycrinidae, and the non arm-branching Camerata of other families, 

 are the openings for pinnules which are to a greater or less extent 

 incorporated in the calyx, and emerge directly through the wall 

 along the margin where the dorsal and ventral structures meet, 

 analogous to the oral pinnules of the Recent crinoids. It is probable 

 that they occur in all species of Dolatocrinus, unless perhaps in some 

 where the arms become free directly upon the first secundibrach. 

 In several cases where the species were described as without "ovarian 

 pores," subsequent inspection has disclosed their presence; and 

 their apparent absence in any specimen maj^ be due to their being 

 obscured by silicification or covered by matrix, or to their incon- 

 spicuous occurrence. They differ in shape and size in different 

 species or groups of species; in some they are indicated by long slits, 

 well exposed and visible at a glance; in some the}" are very small 

 and lie close under the edge of the arm, but are absent in the wider 

 space between the rays, in which case, especiall}' when there is a 

 rugose surface, they are hard to see. 



The elongate slits represent the ambulacral grooves leading to the 

 openings, from which the minute covering pieces have fallen away, 

 a shown by figures 4 and 10 on plate 1. 



10 On the genus Scyphocrinus, 1917, pp". 33-37; 40-46; pi. 9, figs, oa, b, 6; see also pi. 1, figs. 4, 10, and pi. 



2. figs. 3, 4, herein. 



