CALCAREOUS SPONGES. 779 



The only species of this curious genus is Kirk's Zamontia zona 

 from New Zealand, which perhaps forms a transition from the 

 genus Leucmidra to the genus Leucyssa. 



1. L. ZONA Kxrli. 



Lamontia zona Kirk [1894]. 



Genus 42. Leucyssa Haeckel [1872] (emend.). 



Diagnosis. Canal system leuconoid. Skeleton entirely composed 

 of smooth oxea. 



For illustrations of this genus see Haeckel [1872]. 



We can only suppose that this genus, which has only been 

 observed by Haeckel, owes its peculiar skeleton to the complete 

 suppression of ancestral radiates. 



The only known species is : — 



1 . L- spongilla Haeckel. 



Leucyssa spongilla Haeckel [1872]. 



Genus 43. Trichogypsia Carter [1871 B], 



Diagnosis. Canal system leuconoid. Skeleton entirely composed 

 of spined oxea. 



For illustrations of this genus see Haeckel [1872]. 



In 1871 Carter proposed the genus Trichogypsia for his species 

 T. villosa. In 1872, in " Die KalkschAvamme," Haeckel regarded 

 this species as a variety of his Leucyssa incrustans, the specific 

 name incrustans having been given by him without description in 

 1870 under the genus Sycolepis. The diagnosis of Sycolejns also 

 contained no reference to the essential peculiarities of the species 

 in question, and was subsequently abandoned by its author. 



The name Trichogypsia has therefore priority in our opinion 

 over both Sycolepis and Leucyssa, and we have retained it here 

 for species which, like T. villosa, have spined oxea, while using 

 Haeckel's name I^eucyssa for those with smooth oxea. 



We consider that Haeckel's variety lichenoides, which is the 

 first variety of his Leucyssa incrustans, is specifically distinct from 

 Carter's Trichogypsia villosa, and as the name villosa has priority 

 over incrustans, we confine the latter to the form termed by 

 Haeckel var. lichenoides. 



We recognise the following species of this genus : — 



1. T. iNCRUSTAxs HaeckeL 



Leucyssa incrustans var. lichenoides Haeckel [1872]. 



