42 



I. MIMA. 



greater or less quantity. As in terme lia there are only discohexasters or their 

 modification, usually in one or two kinds (macrodiscohexastcrs and microdisco- 

 hoxasters.) 



Artificial Key to Genera and Species. 



■y. Parenchymal rcegascleres extensively (used together 



I)'. Di-cohexaster in one kind Earyplejma auriculare. 



li". Di cohexaster in two kinds (including "rhopa'aster") iulocaiyx irregularis. 



a". Parenchymal niegascleres loo-ie (exc?pt at surface of at- 

 tachment). 



b'. Dermalia pronged Cavlocalyx tener. 



b // . Dermalia without prongs. 



c'. With hexactinose discohexaster. 



(K. Kays of parenchymal hexactins straight Leucopwau orthodoau. 



d". Rays of parenchymal hexictins curved [jtucopzacux skolindocus. 



c" . Without hexactinose discohexaster. 



d'. Discohexaster in one kind ffacopegma solulum. 



A". Discohexaster in two kinds (minute clavicome and 

 very large discohexaster with anchor-like terminal 



disc?) Chaunnplectella cavernosa. 



Leucotsacus, n. g. 



Small, sack-like forms with smooth surface. Parenchymal niegascleres con- 

 sist chiefly of hexactins ; diactinic parenchymalia present, but play a subordinate 

 part. Intermedia are usually of two kinds : wiacrodixeoliexaster hexactinose, 

 i. e., six-armed as in a regular hexactin ; each arm, or more properly terminal, 

 ends with an anchor-like umbel of 3 — 5, strong teethf ; length of arm 50 — 90 jx. 

 microdiscohexader, of variable shape and size. Gastralia are usually hexactins, 

 differing in no way from those of parenchymalia. 



1. L. orthodocus, n. sp. 



Body ovoid, with stalk-like base ; 1 mm. long. Rays of dermal pentactins 

 and of parenchymal or gastral hexactins straight. Hexactinose macrodisco- 

 hexaster as already characterized. Microdiseohexaster 50 — 88 m in diameter ; 



each short principal with 4 — 8 slender terminals, which together from a bell- 

 shaped perianth ; terminal disc with 5 or fi minuts teeth. 

 Loc. : Sagami Sea. 



t Thespicul here characterized has been figured by ScHrxzE, Chall. Rep. Hex. Pl. LV, 

 fig. 8. In this peculiar modification of discohexasters the axial cross is confined to the centre. 



