MACCOYA. 321 



outer aspect of ambulacral plates in Maccoya intermedia (Plate 33, figs. 7-9). The larger 

 hexagonal interambulacral plates measure 7 to 7.4 mm. in width, and 5.8 to mm. in height, 

 so that they are distinctly wider than high. They have numerous secondary tubercles like 

 those of Plate 32, fig. 4. 



Of the specimens in the Sedgwick Museum, Cambridge, England, that from Clitheroe, 

 no. 17, from the Aitkin Collection, consists of portions of ambulacra and dissociated interambula- 

 cral plates. Of the ambulacrals, all plates cross the half-areas, but alternate plates arc partially 

 pinched off marginally, and pore-pairs are biserial, as in Plate 34, fig. 8. Another specimen, 

 from Hook Head, Ireland, no. 1, is the original specimen referred to by Keeping (1876, p. 38). 

 What he described as an ocular plate with two pores, lies above an interambulacruin, thmifih 

 it is not in place. In my opinion it is not an ocular, but a genital, high, as usual, and with 

 three pores, not two. There are some ambulacral plates in place and five columns of inter- 

 ambulacral plates, consisting of one column of pentagonal adradial, and four columns of rather 

 low hexagonal plates. One or more columns are evidently wanting. A third specimen from 

 Hook Head, no. 5, from the Walton Collection, consists of a portion of an interambulacrum, 

 with four columns of plates in place, one column of pentagonal adradial and three columns 

 of low hexagonal plates, which measure about 7.5 mm. in width by 5 mm. in height. 



* Maccoya gigas (M'Coy). 

 Plate 46, figs. 1-3; Plate 47, figs. 1, 2. 



Palaechinm gigas M'Coy, 1844, p. 172, Plate 24, figs. 4a-4c; Dujardin and Hupe 1 , 1862, p. 463; Buily, 

 1874, p. 41, Plate 3, figs, a-d; Quenstedt, 1875, p. 380, Plate 75, fig. 40; Keeping, 1876, p. 38, Plate 

 3, figs. 12, 13; Julien, 1896, p. 130; (pars) Klem, 1904, p. 32. 



MacCoya gigas Pomel, 1869, p. xlvi. 



Palaeechinus gigas Loven, 1874, p. 41 (non Duncan, 1889, p. 198, text-fig, i; non Jackson, 1896, p. 204, 

 Plate 7, figs. 38, 39 J ). 



Maccoya gigas Pomel, 1883, p. 115; Lambert and ThieYy, 1900, p. 119. 



Non Palechinus gigas Tornquist, 1897, p. 739, which is based on Duncan's Palaeechiiius gigas. 1 



The cotypes of this species which are in the Science and Arts Museum, Dublin, are the 

 basis of M'Coy's and Baily's observations and also of my diagnosis. The whole test is unknown, 

 but the parts which are known indicate that it was high, spheroidal. M'Coy's restored figure is, 

 I think, much too low. Ambulacra are relatively narrow, about 10 mm. in width, and as shown 

 by Baily, are composed of two columns of low plates, all of which meet the middle of the area, 

 but marginally alternate plates are primaries, reaching the interambulacra and enlarged at 



1 Duncan's and Jackson's observations were apparently both based on the specimen in the Museum of Practical Geology 

 which has a different ambulacral structure from Maccoya, and is here referred to Loveitechinus anglicus sp. nov. (pp. 304, 

 346, Plate 46, figs. 5-6; Plate 47, figs. 3-5). 



