8 E. 0. Joshua : 



I found tlint it varied iK't (Hily in different specimens. l)ut in 

 different nix-as of tlie same individual. In some eases (jne of the 

 muscles would l)e divided in two for some part of its length ; I think 

 that both this and tlie otlier condition refei'red to must be assigned 

 to the state of contraction of tiie ciicular muscles. Tlie ari-ange- 

 ment of the wlieel papilae is subject to variation ; thev frc(piently 

 occur in all tlie radii. The polian vessels were very numei-ous 

 and variable in size in the animals I opened. 



Chiridota ixgens, sp. n. 



Sea Hall (9). 

 Dr. Hall very kindly placed at my disposal a slide containing 

 the Chiridota spicule, referred to in the above paper. It has been 

 presumed to be a tertiary fossil, and I am inclined to think i-ightly 

 so. The wheel is exceptionally large, 200 f>. in diameter, and of 

 tlie usual Chiridota character. Although collected from a situa- 

 tion in close proximity to the sea, it diffei's from the ossicle 

 peculiar to tlie two Chiridotidae, found in the locality, viz., 

 C r/ir/aa, and T. roehuchi ; the wheels of the foi-mer average 112 

 fx in diameter, and of the latter, 80 /<. In view of the circum- 

 stances under wliich it was found, I propose regarding the species 

 as new. Hall's figure conveys a good idea of the structure of the 

 spicule. 



GENUS TROCHODOTA. 



Trochodota allani (Joshua). (Plate I., Fig. 3). 



Taeniogyrus allani Joshua (11). 

 Chiridota allani Dendy (7). 



Localifies. — Port Phillip Bay, Westernport Bay, Corio Bay. 



This species is extraordinarily abundant on the sludge baidvs 

 which form (the greater part of the bottom of Port Phillip Bay. 

 I have seen the dredge presenting tlie appearance of having been 

 dragged through a mass of lilood slime, from tlie thousands of 

 this species adhering to it. Accompanying it, usually, are al)out 

 one per cent, of Lepfos//napfa dolahrifera. 



Professor Dendy very kindly compared specimens of tliis animal 

 with those of ('hiridnfa di/nedinensis Parker, witli wiiich it was 

 at one time thought to be identical, and was able to conHrm the 

 differences I pointed out in my original description of the species. 



(II.) For reasons given in my note on Taxonomy elsewhere, I 

 have abandoned my recognition of Taetiiotji/DtK as a genus, and 

 noAV assign this species to Ludwig's Trochodofa. 



