THE COLLECTION 01" MISS H. GATTT. 145 



from whose account it would seem to be a singularly undefined 

 and heteromorphic hydroid, old specimens combining characters 

 of Sertularia, Thuiaria, Selaginopsis, and DesmoscypJius. 



Thuiaria. 



Thuiaeta ustteeeupta, n. sp. (PI. XVI. figs. 8-10.) 



Tropliosome. — Stem monosipbonic, carrying pinnately disposed, 

 rather closely-set alternate ramuli. Hydrothecge borne both by 

 stem and ramuli, nearly opposite, deep flask-shaped, closely set 

 upon the pinnae in groups of four or five pairs, the groups 

 separated from each other by deep constrictions of the pinna. 



Gonosome not present. 



Locality. Australia. 



This is an easily recognized form, characterized by the distinctly 

 separated groups in which the hydrothecse are disposed on the 

 pinnae, and which are quite obvious to the naked eye. The 

 hydrothecse in each group overlap one another ; their margin is 

 thin and collapsable, and it is difficult to obtain from the dried 

 specimen a satisfactory view of it. It would seem, however, 

 to have two small lateral teeth. 



The stem is cylindrical, carrying two rows of subopposite, 

 entirely separate hydrothecse. A narrow, but well-marked joint 

 is present just below the origin of every pinna, and the stem is 

 marked in its entire length by close delicate longitudinal sulci. 

 Each pinna commences by a very short, narrow, cylindrical joint, 

 which is supported by a projecting process of the stem. 



The stem attains a height of about 3 inches. 



Thuiaria diaphana, Busk in litteris, n. sp. (PI. XVIII. 

 figs. 1-3.). 



TropTiosome. — Colony attaining a height of 9 inches; stem 

 strongly fascicled towards the base, becoming monosiphonic 

 distally, irregularly branched, and set along its length with close 

 pinnately disposed alternate ramuli. Hydrothecse alternate, 

 closely set, deep, nearly cylindrical, adnate for their entire height 

 to the internode, and with an even circular orifice, four pairs 

 usually carried on an internode. 



Gonosome. — Gronangia carried along one side of the pinnae, 

 cylindrical, with the summit abruptly truncated, and the margin 

 of the orifice very slightly everted ; walls of the gonangium with 

 shallow longitudinal plication. 



Locality. Moreton Bay, Queensland. 



This beautiful species is remarkable for the delicacy and 



