ciAHK] HEMI ASTER CALVINI — LINTIITA TUMIDULA. 91 



ami br«l\dly triiiieateJ on the imsterior margin. The anterior suh-us is 

 shallow, and produces but a feeble groove ou the anterior margin. The 

 base is flat. 



The ambulacral areas are narrow. The ]>oriferous zones are broad; 

 the i»etals moderately depressed and of good length; the pores in the 

 petaloidal portions of the paired and)ulacra elongated, slit-like (PI. 

 XLix, Fig. lie), those of the unjiaired ambulacrum small and approxi- 

 mated (PI. XLIX, Fig. 2(j). Beyond the petals the pores are very small, 

 and oc(;upy the lower outside corner of each plate (PI. XLiX, Fig. 2/). 



The surface of the plates is covered with small perforated tubercles, 

 rather widely s(;attered, between which a microscopic granulation in- 

 tervenes. The peripetalous fasciole is indistinct. 



The apical disk is small, compact, and nearly central (PI. XLix, 

 Fig. 2i). 



The mouth opening is small, transversely oval, and situated at a dis- 

 tance from the margin. 



The anal opening is oval and situated high on the truncated surface 

 of the ]>osterior margin. 



Related forms. — Hemimter Galvlni is most <dosely related to H. tex- 

 anus, from which, however, it is separated by its more elevated form 

 and small, luirrow, anterior sulcus. The apical disk is also more ex- 

 eeutric. 



Locality and geoloffical horizon. — Hem i aster Calvini is from the Shoal 

 creek limestone at the top of the Comanche series (lower Cretaceous) of 

 Texas. It is found in Travis county. 



Collections. — U. S. National Museum; University of Iowa. 



LINTHIA Merian. 



LiNTHiA TUMIDULA Clark. 



Plate L, Figs. la-i. 



Linlhia ttimldula Clark, 1891. Jolius Hopkins Uuiversity Circulars, No. 87, p. 77. 



Determinative characters. — Test oval, cordiform, elevated; apex cen- 

 tral; posterior border obliipiely truncated, anterior portion grooved by 

 narrow sulcus; sides sloping. Ambulacral furrows long, straight, de- 

 pressed ; poriferous zones broad, pores oval. Apical disk small, nearly 

 central. Anal opening on truncated posterior border. Peripetalous 

 and lateral fascioles distinct. 



Dimensions. — Length, 2^ inches; width, 2 inches; height, 1^ inches. 



Descrijjtion. —Thifi large form has an elevated test, with fiattenedi 

 sloping sides, oval outline, and a narrow, moderately depressed anterior 

 sulcus that grooves the anterior margin. The base is flat, except for 

 the peristomial depression. 



The ambulacral areas are narrow and furrow for a long distance the 

 upper surface of the test to a moderate depth. The poriferous zones 



