LAGANUM PUTNAM r. 519 



Kingsmills Islands ; Feejce Islands ; Philippine Islands ; Australia ; Zanzibar. 



Laganum Putnami 



! Laganum Putnami Barx., 1863, in A. Ac, Proc. Ac. N. Sc. Phila., p. 359. 



From the figures and descriptions alone this species would be referred to 

 L. stellatum ; an examination of the originals has, however, shown that L. 

 stellatum, from its internal structure, was only a }'oung L. Peronii. There 

 is considerable confusion in the identification of the species of Laganum 

 with genital pores outside of the apical system, which can only be settled 

 after examining the internal structure. Laganum Putnami would undoubt- 

 edly pass as a variety of L. Peronii, to judge from its exterior alone. It 

 shows, when seen from the interior, only a couple of thin walls, concentric 

 with the edge, as in all Laganum species, while in much smaller specimens 

 of L. Peronii, the peculiar fan-shaped and radiating partitions and walls 

 already extend a considerable distance towards the actinostome from the 

 edge of the test. The outline of this species is quite pentagonal, with 

 rounded angles, resembling in general facies L. depressum, concentric apex, 

 but with more lanceolate and pointed petals, of uniform length, the an- 

 terior pair somewhat shortest ; the genital openings placed at about one 

 quarter the distance of the apex from the edge outside of the apical system. 

 The median interambulacra rising from the apex as a bare rounded ridge 

 from the apical system, and extending like spokes from the genital openings. 

 The tuberculation is distant, small ; the miliaries closely packed, minute ; 

 towards the edge the tubercles are larger and more closely crowded ; on the 

 actinal side they are large and well separated. The ambulacral furrows are 

 deep, extending almost to the edge of the test. The anus of the only speci- 

 mens I have examined, which were of same size, is about its diameter from 

 the edge of the test. 



Long. Trans. Post. Dist. Genit Op. Dist. Anus 



Diam. Diam. Pair Amb. from Apes. from Edge. 



29.4 25.9 10.4 4.6 2.1 



Japan. 



