STRATA OF JAVA. 75 



identity of these specimens with T. toreumaticus , the more 

 so as the abactinal system, which is very well preserved 

 in some of these Japanese specimens , exactly corresponds 

 to that of 2\ toreumaticus. For this reason I feel justi- 

 fied in regarding 2'. areolatus and T. caelatus as varieties 

 of T. toreumaticus. 



3. Pleurechinus Jaranws nov. spec. The test of 

 this species is high , spherico-pentagonal. The ambulacral 

 areas have more than half the width of the interambulacral 

 areas. The poriferous zones are narrow, straight, with 

 simple , unigeminal pores ; three pairs of pores belong to 

 one primary plate. There are deep pits along the hori- 

 zontal sutures of all coronal plates. Vertical ridges unite the 

 plates of the same row , bridging these intervals. As the 

 plates gradually acquire greater width towards the middle 

 of the test, the number of the vertical connecting ridges 

 increases from one to three, five and even seven; the 

 middle one (the primary ridge , corresponding in position to 

 a primary tubercle) being always the strongest. When there 

 are seven, the two widest apart are exceedingly small. 

 On the ambulacral areas the connection of the plates is 

 brought about, firstly by primary ridges corresponding as 

 before to primary tubercles and situated exteriorly in the 

 immediate neighbourhoud of the poriferous zone, secondly 

 by secondary ridges. Of the latter there are never more 

 than two, in accordance with the lesser width of the am- 

 bulacral areas. As all the connecting ridges of the coronal 

 plates have the same direction , they give rise to a graceful 

 system of parallel stripes, which cover the whole test. 



In addition to the primary tubercles (situated on the 

 middle of the plates belonging to the interambulacral areas 

 and on the inner border of the poriferous zone on those 

 plates, which belong to the ambulacral areas) we find on 

 all the plates tubercles of the 2"'i and 3'1 order , which ho- 

 wever do not correspond to the secondary ridges. The 

 actinal and abactinal systems are subcircular. 



The dimensions of the largest of eight specimens examined are: 



J^otes trpm the Leyden Museum , A"ol. l\. 



