﻿112 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



liinule. It also extends to within 5.5 of the ambnlacral notch of the 

 area in which it lies. Ambulacrum IV is much shorter than ambula- 

 crum V, measuring 30 mm. in length and 12 mm. in width at its 

 Avidest part. This ambulacrum extends to within 3.5 mm. of its 

 marginal notch. The features of the ambulacra V and IV, as de- 

 scribed, indicate the character of ambulacra I and II, which are only 

 preserved in part in the holotype, though one of the fragments has 

 ambulacrum II quite perfectly preserved. Ambulacrum III is repre- 

 sented only in part (for a length of 25 mm.) by the left side of its 

 petaloid area; it probably had about the length and width of the 

 petal of ambulacrum I"S', as in the allied species Encope maci^ophora 

 Ravenel. Ambulacral furrows on the ventral side are deep, strongly 

 marked, with some forking near the periphery of the test. The inter- 

 ambulacra are very wide, not narrowing markedly near the apical 

 disk. Minute tubercles cover the dorsal surface of the test, and ven- 

 trally the tubercles are larger excepting on the lines of ambulacral 

 furrows, where they are minute or wanting. Details of the apical 

 disk, peristome and periproct are entirely wanting. This species does 

 not make a close approach to any other Imown species, but its nearest 

 ally is Encofe macrophora Ravenel from the upper Miocene of 

 South Carolina and the Pliocene of Florida.^ 



Locality and geologic occurrence. — Gatun formation, Miocene, 

 Panama Canal Zone. From 85-foot cut north side of big swamp on 

 relocated line, Panama R. R., about one and one-half to two miles 

 bej'ond Camp Cotton, toward Monte Lirio, D. F. MacDonald and 

 T. W. Vaughan, collectors, 1911. Fourteen specimens, including 

 fragments, U. S. National INIusemn station No. 6030. 



Type.—Q'AL No. 32M56, U.S.N.^kl. 



ECmNOLAMPAS SEMIORBIS Guppy. 



EcJdiiolaiiipas scniiorhis Guppi', Ou Tertiary Ecliinoderms from the West 

 Indies, Quart. .Journ.. Gool. Soc. London, voL 22, 1866, p. 299, pi. 19, 

 fig. 7. — CoTTEAU, Echinides Tertiares des lies St. Barthelemy et An- 

 guilla, Kongl. Svensk. Vetenskaps. Akad, vol. 13. 1ST5, p. 24, pi. 5, 

 figs. 1-2; pi. 6, fig. 1.— Jackson, Proc. U. S. Nat. Mus., vol. 53, 1917, 

 p. 498. 

 This species is abundant in the Oligocene Tertiary of the West 

 Indies, material from Anguilla having been described by Guppy, and 

 Cotteau erroneously records it from St. Bartholomew. Dr. T. Way- 

 land Vaughan in 1911 collected al3U]idant, fine specimens in the Island 

 of Anguilla. 



From the Panama Canal Zone a number of specimens were col- 

 lected from a hard gray limestone. The specimens are for the most 

 part uncompressed and in very good condition of preservation. One 



J Clark, William Bullock, and Twitchell, Mayville W. Mesozoic and Cenozoic Echino- 

 dermata of the United States. Monograph, U. S. Geol. Survey, vol. 54, 1915, p. 206, 

 pi. 93, figs. 2a-e; pi. 94, figs. la~f. 



