344 



4.. Terebratula septentrionalis (pi. lxviii. f. 5, 6.) Couth. 



Testa subovata, postice subacuminata, obtusa, albicante; valvis 

 subsequaliter convexis, longitudinaliter radiatim costellatis, costellis 

 tenuissimis bifurcatis, subrugosis ; linea marginali lateribus flexu- 

 osis, antice rectiuscula ; foramine majusculo, haud integro, sub- 

 obliquo ; area cardinali subdepressa, deltidiis parvis, fere obsoletis ; 

 ossiculo interno parvo, -| longitudinis valvre, antice arcuato, superne 

 ramulo ad utrumque latus, in medium connexis ; margine interno 

 valvarum minutissime crenulato. 



Shell subovate, slightly acuminated but obtuse posteriorly, 

 nearly white ; valves nearly equally convex, longitudinally radi- 

 ately costellated, the little ridges very slender, dichotomous and 

 roughish: marginal line flexuous on the sides, nearly straight in 

 front : perforation rather large, not complete ; somewhat oblique ; 

 cardinal area rather flattened, with small, nearly obsolete deltidia ; 

 internal appendages small, f of the length of the valve, arched in 

 front with a little branch above on each side, joined in the middle ; 

 inner margin of the valves minutely crenulated. 



Distinguished from T. Caput-serpentis by its much finer radiating 

 strise, its larger and less oblique foramen, and by its rather more 

 extended and somewhat differently formed internal appendage. 

 We have represented two varieties from the coast of Maine, Mas- 

 sachusets, obligingly forwarded by Dr. Gould of Boston. 



5. Terebratula Japonica (pi. lxviii. f. 7, 8.) nobis. 



Testa oblonga, antice rotundata, tenui, albicante, valvis subse- 

 qualiter convexis, longitudinaliter radiatim striatis, striis numerosis, 

 subirregularibus, subbifurcatis ad lateres prope cardinem confer- 

 tiusculis ; lateribus prope cardinem subplanulatis ; linea marginali 

 rectiuscula, ad lateres postice declivi ; valva dorsali postice sub- 

 producta, truncata, foramine mediocri, haud integro, perobliquo ; 

 area cardinali iuconspicua, deltidiis obsoletis ; ossiculo interno 

 parvo, | longitudinis valvse, ramulos duos angustos, demum amen- 

 tum latum flexuosum sistente : marginibus valvarum minutissime 

 denticulatis. 



Shell oblong, rounded in front, thin, whitish, valves nearly 

 equally convex, longitudinally radiately striated, striae numerous, 

 rather irregularly dichotomous and very close-set on the sides near 

 the hinge ; the sides near the hinge rather flattened ; marginal 

 line nearly straight, inclining to the sides near the hinge ; dorsal 

 valve somewhat produced posteriorly and truncated, with a mode- 

 rate sized very oblique and incomplete perforation ; cardinal area 

 indistinct, with obsolete deltidia ; internal appendages small, ] the 



