ON THE p]XPERIMENTAL HYBRIDIZATION OF EGHINOIDS. 



837 



the triphyllous pedicellariae are likewise of the sort characteristic of this species. 

 The most important, however, are the globiferous pedicellarife, which are exactly 

 intermediate in structure between those of E. miliaris and E. acutus. There are 

 some teeth along the side edges of the end part of the valve (the blade) as in 

 E. miliaris, though there are not quite so many as in this species. The end portion 

 of the valve forms an open furrow, which, however, is much narrower than in 

 E. miliaris and more like E. acutus. In E. acutus it forms a tube which is almost 

 closed. The size of these pedicellarias is more or less intermediate between that ot 

 both parent forms (see text-figs. 18-20). 



Text-fig. 18. — Pedicellarise of E. acutus. A, lateral view; B, full vieAv of same, x 170. 



The fact that all the ambulacral plates carry a primary spine is of special 

 importance, as this is a decided E. viiliaris character, of which there can be no 

 doubt. The other characters of a maternal origin are undoubtedly the general 

 colour of the test and spines and the plating of the buccal membrane. Of these the 

 colour is never so well marked as in the pure E. inilinris, and when the hybrid is 

 examined in bright light there is something that suggests even the red colour of 

 E. acutus. There is always a certain amount of dark brown pigment, shown in 

 figs. 105 and 107, which is never present in E. miliaris ; it is undoubtedly of paternal 



VOL. CCIV. — B. 2 X 



