io6 Bulletin 39 378 



early sulcated whorls of typical tulipa, as fignred by Dr. Dall. 

 They however become smooth somewhat earlier and the fragment 

 of the spire shows the succeeding whorls to be smooth and lack- 

 ing the sulcated sutural band as in distans. 



The Fasciolaria semistriata Sowerby is an allied but distinct 

 species from the Miocene of Santo Domingo, and likely to be dis- 

 covered in the Gatun beds of Costa Rica and Panama. This as 

 may be seen from the new figure of Dr. Maurj^, (Bull. Amer. 

 Pal., vol. 5, p. 244, pi. 13, fig. i), differs conspicuously from the 

 distans and tidipa, with which it was united by Gabb, by its 

 deep sutural depressed band, which gives to the whorls, a very 

 convex or even shouldered appearance. The early whorls are 

 spirally sulcated as in tulipa, but have in addition knob-like ribs, 

 like those seen on F. gorgasiana. 



Uscari Stage: Port Lwion. 



Fasciolaria T^'lacDona^di, n. sp. Plate 8, figure i 



Shell large, (type specimen imperfect, with only the last two 

 whorls preserved); number of whorls unknown; the spire-whorls 

 are angled about the middle, forming a board, sloping shoulder 

 above; the last whorl has the shoulder about the upper third; the 

 sculpture is predominantly spiral, consisting of numerous, fine, 

 alternating threads, which are slightly roughened by the growth 

 lines; the angle of each whorl is longitudinally undulated by 12 

 faint ribs; anterior canal is nearly straight with two faint plicae; 

 outer lip sharp. 



lycngth (2 whorls) 70, diameter 37 mra. 



Of this large and elegant species, only a single imperfect 

 specimen with less than two complete whorls preserved, was col- 

 lected from the Gatun beds of the Banana River, Costa Rica. It 

 differs from the more common F. Gorgasiana, by its persistent 

 and rough spiral sculpture and less heavily tuberculated should- 

 er. 



This species is named in honor of Dr. D. F. MacDonald, well- 

 known for his geologic work on the Isthmus, during the con- 



