128 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



Shape. — ]\Iedium to large, larger specimens 65 mm. long, elongate 

 to broad, width less than length ; adapical surface highly inflated with 

 greatest height posterior to center, gently sloping anterior surface, 

 steeply sloping, slightly truncated posterior surface ; adoral surface 

 flat. 



Apical system. — Slightly anterior, tetrabasal (text fig. no), genital 

 2 extending posteriorly separating posterior genital plates ; four 

 genital pores. 



Ambulacra. — Petals broad, equal, closed, with broad tapering inter- 

 poriferous and poriferous zones; conjugate pores, outer pore slitlike, 

 inner slightly elongated transversely. 



Periproct. — Supramarginal, high on oblique posterior truncation, 

 betvveen one-half and two-thirds distance from apical system and 

 posterior margin ; longitudinal, forming notch in overhanging dorsal 

 surface. Deep, broad depression ventral to periproct, extending lat- 

 erally across test. 



Peristome. — Anterior, pentagonal, wider than high, flush with 

 adoral surface. 



Floscelle. — Bourrelets strongly developed, jutting into peristome, 

 toothlike. Phyllodes (text fig. in) broad, deeply depressed between 

 bourrelets, single pored with two series of pores in each half ambula- 

 crum, approximately 12 pores in each outer series, 5 or 6 in each 

 inner. Buccal pores widely separated from edge of peristome. 

 Sphaeridia in two series in middle of ambulacrum. 



Tuberculation. — Tubercles considerably larger on adoral surface 

 than on adapical: midzone of interambulacrum 5 with no tubercles 

 adorally. 



Occurrence. — Upper Cretaceous (Upper Campanian), Andra- 

 karaka sandstone, near Andrafiavelo (Maintirano), Madagascar. 



Location of type specimen. — Unknown. 



Remarks. — I suspect that the periproct is not keyhole or flask 

 shaped in 5. galeatus as described and figured by d'Orbigny. Forbes 

 (1846, pi. 19, fig. lb — plates published in 1856) showed a similarly 

 shaped periproct in Stigmatopygus elatus (herein considered Goyi- 

 grochanus herschelianus) , but as first pointed out by StoHczka (1873, 

 p. 27) and confirmed by my own examination of the holot}-pe (see 

 pi. 19, fig. 6) , the periproct is round to oval, but has a broad, trans- 

 verse depression ventral to it which, when combined with it, gives the 

 appearance of a flask-shaped periproct. The periproct in 5". lamberti 

 is very similar in appearance. Probably in d'Orbigny's specimen of 

 5". galeatus the depressed area ventral to the periproct was partially 



