192 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



alternating. Rays five, long, thick, and rounded in section. Disk 

 not large. 



This family contains: 

 Jaekelaster Stiirtz. 

 Compsaster Worthen and Miller. 



Genus JAEKELASTER Sturtz. 



Jaekelaster STVRTZ,Yevh. naturh. Ver. preusa. Rheinl., etc., vol. 56, 1900, pp. 

 235-236, pi. 4, figs. 13-16. 



Generic cliaracters. — Rays five, thick and long, 55 mm. in length, 

 16 mm. in greatest breadth, rounded distaUy. Disk large. Both 

 rays and disk devoid of marginal plates. 



AbactinaUy without columns of plates, entire surface decidedly 

 and abundantly covered with "paxillse." Madreporite small, 

 subcentral, radiately striate. 



Ambulacral furrows wide, widest at about mid-length and nar- 

 rowing both distaUy and proximally. Two col mns of podial 

 openings. Ambulacraha narrow, L-shaped, shghtly overlapping 

 and slightly alternating proximaUy. Adambulacrals small, di- 

 rectly opposite the ambulacrals. Outside of the rays the integu- 

 ment bears spmes and ''paxillse" abundantly. 



GenoJiolotype and only species.— J. petaliformis Sturtz (citations 

 as above). Lower Devonic of Bundenbach, Germany. 



Remarks. — This genus is most closely related to Compsaster, 

 in fact the general appearance of the two is very much alike. 



Genus COMPSASTER Worthen and Miller. 



Plate 31, figs. 1, 2. 



Compsaster Worthen and Miller, Geol. Surv. Illinois, vol. 7, 1883, p. 327. 



Original description. — "Body stellate; central area or disk com- 

 paratively small; rays large, long, more or less fusiform; grooves 

 deep and bordered by numerous thin, subcircular, adambulacral 

 plates. The ventral side of the typical species shows about six 

 rows of plates upon each side of the ambulacral furrows, which 

 have a regular, transverse as well as longitudinal arrangement. 



"This genus is distinguished from aU others in the family [their 

 Palseasteridse] by the number and form of the adambulacral plates, 

 by the great number of disk plates upon each side of the ambula- 

 cral furrows, and by the general form of the body and rays." 



GenoTiolotype. — C. formosus Worthen and Miller. It is also the 

 only named species of the genus. 



The adambulacral plates in Compsaster appear to be much as 

 in Vrasterella and both genera agree in having no distinct inframar- 



