THE PENNSYLVANIAN PERIOD. 617 



and Eurasia, but into the far Orient and Australasia. Among these 

 wide-ranging species were Hustedia mormoni (Fig. 286, gg), Rhipi- 

 domella pecosi, Enteletes hemiplicata (Fig. 286 hh), Productus semi- 

 reticulatus, P. cora, P. costatus (Fig. 286, v). Some of these, as P. 

 semireticulatus and P. cora, extended up into the Permian. Other 

 representative brachiopods are illustrated in Fig. 286, w, x, aa, bb, cc, 

 ee, ff, and ii. , 



A new phase of the crinoids. — The crinoids were a smaller factor 

 in the fauna than might have been expected from their previous and 

 subsequent history. The cystoids and blastoids seem to have dis- 

 appeared previously, and no starfishes have been recognized, though 

 they were doubtless present; sea-urchins were rare. The camerate 

 crinoids do not appear, and the inadunate crinoids took the leading 

 place, and celebrated their accession to crinoidal supremacy by develop- 

 ing the ventral sac to unseemly dimensions until it sometimes pro- 

 truded beyond the arms with balloon-like, or mushroom-like, inflation 

 (Fig. 286, m). It is needless to say that these ventral excesses did 

 n:t last long, and the moral is obvious. Other genera developed 

 in the opposite direction, and lived on becomingly, giving rise, as it 

 would appear, to some of the Mesozoic types. The form Eupachy- 

 crinus magister (Fig. 286, n) is notable as bearing a Mesozoic aspect. 



were nearing the time of their extinction, and (3) the conservative, simple sutured 

 nautiloids which persisted from the Ordovician to the present. In the Carbon- 

 iferous, the nautiloids were especially characterized by their nodose ornamen- 

 tation. Brachiopods: t, Productus symmstricus MeCh., u, Productus nebrascensis 

 Owen, v, Productus costatus Sow ; the genus Productus is one of the most com- 

 mon in the Carboniferous faunas, and these are three of the common species; 

 w-x, Derbyia crassa (M and Ff.), representative of a genus which is the direct 

 descendant of Orthothetes of the Devonian and Lower Mississippian; it differs 

 from that genus in the presence of the median septum, seen in w\ y, Spiriferina 

 kentuckiensis (Shum.), a common Carboniferous species; the genus Spiriferina 

 differs from Spirifer in its punctate shell structure and its median septum; it 

 does not occur below the Mississippian, but extends into the Mesozoic; z, Chonetes 

 grannlifera Owen. This genus occurs from the Silurian to the close of the Paleozoic, 

 and is common from the middle Devonian up; it is characterized by its concavo- 

 convex form, and the spines along the hinge-line; aa, Seminula argentea (Shep.), 

 a spire-bearing, atheroid shell, one of the commonest Carboniferous species; a 

 near realtive is S. subquadrata of the Genevieve fauna (see Fig. 237, I) ; bb, Die- 

 lasma bovidens (Mort.), a common, loop-bearing shell of the Carboniferous; cc, 

 Phipidomella pecosi (Marc), almost the last representative of the orthid shells 

 which were so abundant in the Ordovician (see Fig. 163); dd, Spirifer cam eratus 

 Mort., a very characteristic member of this fauna; ee, Pugnax uta (Marc), one of 

 the rhynchonelloid shells; //, LinguJa umbonata Cox; the Lingulas persisted iroai 

 the Cambrian to recent time; gg, Hustedia mormoni (Marc), a small, plicated, 

 spire-bearing shell; hh, Enteletes hemiplicata (Hall), a peculiar orthid genus found 

 only in the Carboniferous; ii, Meekella striatocostata (Cox), a peculiar stropl.o- 

 menoid shell, probably an offshoot from Derbyia. 



