NATURAL SCIENCES OF PHILADELPHIA. 395 



branch of the saddle being bilobate ; superior lateral lobe one-fourth longer 

 than the dorsal lobe ; extremity divided into two very long slender parallel 

 branches, the one on the dorsal side trifurcate, the other simply serrate and 

 sometimes curved towards the other ; above these on each side are two 

 smaller processes, the upper one smallest, and those on the dorsal side some- 

 what larger ; superior lateral saddle wider than the dorsal, of the same gene- 

 ral form, except that the dorsal side is widest ; lateral lobe about half as 

 large as the superior lateral, bifurcate at the extremity and with one simple 

 process above on each side ; lateral saddle simple, divided at the extremity 

 and not so large as the lobe ; inferior lateral lobe about as large as the pre- 

 ceding saddle, serrate on the sides and bifurcate at the end ; ventral saddle 

 broader than the lateral, about as long and somewhat more profusely lobed, 

 but not so distinctly ; ventral lobe small, trifuroate at the end, and with two 

 or three uniform processes at the sides. 



PI. iii. fig. 1 illustrates the septum and a section of this species taken from the 

 specimen figured by Dr. Morton, loc. cit. PI. 13, f. 10. 



This species can be at once distinguished by its distinct pentagonal form and 

 the two rows of tubercles, one at the edge of the ventral face, the other half 

 way between these and the dorsum. 



Dimensions. Width, - 7 in. ; diameter in the middle, '5 in. ; width across 

 the nodes on the ventral side, '4 in.; width of same between the nodes, *3 in. ; 

 distance longitudinally between the nodes, - 5 in. These measurements may 

 vary slightly in different individuals, but are correct for Morton's original 

 specimen. 



Baculites anceps Lam., An. S. Vert. t. 7, p. 648, No. 2. 



B. vertebralis Defr., D. Sc. Nat. t. 3, Sup. p. 160. 

 B. dissimilis Desm., Jour, de Phys. t. 85, p. 48, No. 3, pi. 2, f. 4 6. 

 B. vertebralis Blainv., Malac. pi. 12. 

 B. Faujasii Haan, Monog. Am. et Goniat. p. 155, No. 2. 

 B. dissimilis Haan, id. 155, No. 3. 

 B. anceps d'Orb., Desh., Brown, Hisinger et auct. 

 B. carinatus Mort., Synopsis, p. 44, pi. 13, f. 1. 

 B. asver Mort., id. p. 43, pi. 1, f. 12, 13, and pi. 13, fig. 2. 

 B. Tippaensis Con. Jour. Acad. Nat. Sci., 2d ser., vol. iii. p. 334, pi. 35, 

 fig- 27. 



B. Spillmannii Con., id. p. 335, pi. 35, fig. 24. 



B. testa compressiuscula,, laevi, transversim undatii vel tuberculata, dorso 

 subacuto vel obtuso, ventre crassiore obtuso ; apertura obliquata, supra elon- 

 gata, acuta, lateribus sinuata ; angulo, 6 ; septis lobatis. 



Shell subcompressed, section variable, sometimes nearly circular or ovoid, 

 at others strongly pyriform. Dorsum subacute, marked by a flattened bian- 

 gular ridge broadly rounded or undulated ; ventrum always broad, regularly 

 rounded. Sides smooth, marked by faint undulations, parallel with the bor- 

 der of the mouth or by large crescentic or triangular nodes, the apex always 

 downwards. Septum : dorsal lobe about as wide as dorsal saddle, deeply 

 emarginate in the middle, each branch with about three serrations internally 

 and one or two externally ; above the latter there are two or three processes ; 

 dorsal saddle divided in the middle, the process on the dorsal side, trilobate, 

 the other bilobate ; superior lateral lobe smaller than the dorsal, divided at 

 the extremity into two compound processes, with two or three smaller ones 

 above on the dorsal side, and one less on the ventral side ; superior lateral 

 saddle as wide or wider than the dorsal and marked in a similar manner ; late- 

 ral lobe like the superior lateral but smaller ; ventral saddle small, simple 

 and trilobate ; ventral lobe smaller than the corresponding saddle, trifurcate 

 at the extremity and with two small processes above. 



It will be seen that, notwithstanding the apparently great external differ- 



1861.] 



