PALAEECHINIDAE. 303 



Pomel (1869, 1883), the first reviser, included in Palaeechinus those species in which am- 

 bulacral plates are all primaries and pore-pairs are uniserial, and listed as belonging to this 

 genus P. quadriserialis Wright, P. ellipticus M'Coy', and P. elegans M'Coy. Duncan (1889a, 

 p. 3) objected to Pomel's methods and would not accept his genera. I sympathize with his 

 feeling, but cannot see that this is any reason for rejecting Pomel's names. Duncan (1889, 

 p. 205) referred species with this structure (plates all primaries and pore-pairs uniserial) to the 

 genus Rhoechinus of Keeping, which was a mistake, as Rhoechinus (here, p. 394, considered a 

 synonym of Lepidechinus Hall) has imbricate plates, thus differing essentially from Palaeechinus.^ 



Pomel (1869, 1883) further proposed Maccoya as a genus to include species in which am- 

 bulacral plates are alternately enlarged and reduced toward the exterior border, from which 

 result two vertical series of pore-pairs in each half-area. Expressed in other words, the genus 

 Maccoya is characterized by ambulacral plates, all of which reach the middle of the area, 

 but which are alternately primaries and nearly or quite occluded according as they extend 

 to the interambulacrum or not, and with pore-pairs biserial. Pomel's type of this genus is 

 Maccoya gigas (M'Coy), and his observation (1883) was probably based on Baily's (1874, 

 Plate 3, fig. c) figure which is here reproduced as Plate 47, fig. 2. He also and quite correctly 

 included in his Maccoya the Palaechinus burlingtonensis Meek and Worthen and P. gracilis 

 Meek and Worthen. Pomel's (1883) Eriechinus with Palaechinus sphaericus M'Coy as a 

 type (?) , and his Wrightia (1869) (or Wrightella, 1883), with Palechinus phillipsiae Forbes 

 as a type I do not recognize as distinct from Maccoya, because in both the true sphaericus and 

 phillipsiae the ambulacral details and other structures as known are essentially the same as 

 in Maccoya. In brief, I include in Maccoya the species burlingtonensis Meek and Worthen, 

 intermedia Keeping, phillipsiae Forbes, sphaerica M'Coy (but not the sphaericus of Koninck^), 

 gigas M'Coy, and gracilis Meek and Worthen (p. 312). Duncan in his (1889) discussion 

 included in his Palaeechinus part of the species here referred to Maccoya and two species 

 here referred to Lovenechinus. In his Palaeechinus he included P. gigas (p. 304), P. sphaericus, 

 P. ellipticus , P. intermedius, P. phillipsiae, and suggested, quite correctly, that the two North 

 American species (P. burlingtonensis and P. gracilis) belong in the same generic group. Duncan 's 

 (1889) Palaeechinus ellipticus is not the Palaeechinus ellipticus of M'Coy as stated. 



' Palaeechinus ellipticus M'Coy (p. 307, Plate 29, fig. 2; Plate 30, fig. 10) belongs in this genus, as stated by Pomel 

 but the specimen in the Museum of Practical Geology, figured by Duncan (1889, p. 206, fig. viii) as ellipticus is not that 

 species, but is here referred to Lovenechinus lacazei (p. 329, Plate 36, fig. 1). 



^ Professor Duncan included in his Rhoechinus, R. irregularis Keeping (here referred to Lepidechinus, p. 396) ; R. 

 elegans (M'Coy); R. quadriserialis (Wright); R. sp., a specimen in the Woodwardian (now called Sedgwick) Museum, 

 Cambridge, England. See footnote p. 394. 



^ Pomel's (1883) Eriechinus was evidently based not on M'Coy's sphaericus but on de Koninck's (1869, 1870) figure 

 of what he called Palaechinus sphaericus. Pomel says of Ills genus that it differs by the structure of the ape.x, one of the 

 genitals having only a single pore, and this structure is that shown by de Koninck. De Koninck's observations were 

 incorrect, and his specimen was not Palaechinus sphaericus M'Coy, but is here referred to Lovenechinus lacazei (Julien), 

 where it is fully described (p. 330-334, text-figs. 240-243; Plate 35, fig. 7). 



