AR^OSOMA EURYPATUM. 181 



Araeosoma pellucidum A. Ag. and CL 



AsthenoBoma pellucidum A. Agassiz, 1879. Proc. Am. Acad., XIV, p. 200. 1881. 



"Challenger" Ech., Pis. XVIII, figs. 1-6; XIX, figs. 1-6; etc. 

 Hapalosoma pellucidum Mortensen, 1903. " Ingolf " Ech., pt. I, p. 56. 



East Indies ; 100-129 fathoms. 



The small size, pretty colors, and very narrow ambulacra combine to 

 make this a very easily recognized species. The "Albatross" specimens 

 which are less than 50 mm. in diameter, and intermediate in size between 

 those figured on the " Challenger " Ech. PI. XIX, figs. 1-6, were taken at 

 the following station : 



Station 4934. OfP Kagoshima Gulf ; 30° 58' 30'' N., 130° 32' E. 103- 

 152 fathoms. Rocky. 



Three specimens. 



Araeosoma eurypatum A. Ag. and Cl. 



Plates 66, figs. 18-19; 73-75. 



As far as can be judged from the single specimen of this species, the test 

 must have been very flexible, the outline was lobed, the median ambulacral 

 and interambulacral lines bulging out beyond the vertical furrow formed at 

 the junction of the ambulacral and interambulacral zones (PI. 73). The 

 curve of the test at the ambitus is high, projecting well beyond the concave 

 abactinal surface of the test at the centre of which rises the abactinal system 

 (PI. 73, fig. 1). This is well seen in the profile view of the test (PI. 73, fig. 2) 

 as well as in the figure taken from the actinal side (PI. 74), which also shows 

 the ambitus swelling well above the concave actinal surface in the centre of 

 which rises the highly arched, slightly conical actinal system. The test of 

 the specimen figured is, as far as it can be measured in its dry and some- 

 what folded state, 140 mm. in diameter; the actinal system is 35 mm. 

 across, while the abactinal measures 20-25 mm. from the distal tip of a 

 genital plate to the distal edge of the opposite ocular plate (PI. 75, fig. 2). 

 From the ambitus to the abactinal system in the ambulacral zone there are 

 42 plates and in the interambulacral zone 32. On the actinal side in the 

 interambulacral column there are 19 plates and in the ambulacral 31. The 

 test of this species is remarkable for the great uniformity in the size of 

 the coronal plates. Those of the actinal side are but little larger than those 

 of the abactinal side (compare Pis. 73 and 74). The interambulacral plates 



