Descriptions of New Species of Dupadce. 207 



species described under Ambulyx, are stated to recede structu- 

 rally from A. sirigilis and A. gannascus, I am prepared to 

 consider the genus as exclusively American. 



XXYI. — Descriptions of New Species of PuPADiE. 



By Edward S. Morse. 



Bead November 20, 1865. 



Isthmia ventricosa, nov. sp. 



[ Fig. 1. 



Isthmia ventricosa Morse. 



Animal. — Dorsal and cephalic portions of body, and tentacles jet black. 

 Disk long, narrow, rounded at extremity ; anterior portion of disk dark 

 slate, becoming lighter towards caudal extremity. Tentacles short, very 

 bulbous ; base of tentacles approximating. Cephalic lobes conspicuous. 



Buccal plate wide, narrow, not produced in centre, but slightly curving 

 at ends ; cutting edge regularly waved. 



Fig. 2. Fig. 8. 



Buccal plate of I. ventricosa. Lingual membrane of I. ventricosa. 



Lingual formula 98,-13-1-13 ; central and lateral plates notched at 

 outer posterior corners. Central olate |quare, having three small den- 

 ticles. Plate indented at base of central denticle, which is the largest. 



