158 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLDME 1 



(associations), p. 45 (various localities in Western Australia; notes). — Cotton and Godfrey, 

 Roc. South Australian Mus., vol. 7, 1942, p. 232 (type locality; distribution).— H. L. Clabk, 

 Echinodcrra fauna of Australia, 1946, p. 00 (distribution in Australia, Port Jackson record 

 needs confirmation). 



Diagnostic featvres [by A.M.C.].— Tlie ccntrodorsal is discoidal, witli the dorsal 

 pole quite flat although variable in width, the cirrus sockets sometimes encroaching on 

 it; the cirri have up to 13 (rarely 14) segments, of which the longest are not more than 

 half again as long as their median width and the antepenultimate is about as long as 

 broad, but may be broader; the distal half of the cirrus is expanded dorsoventralh^; 

 in length the cirri arc about a fifth the arm length when that is about 35 mm. (a ninth 

 when the arm length is about 60 mm. in the types of Compsometra lacertosa from Port 

 Jackson) ; there are XX-XXX cirri when the arm length is up to 50 mm. (XXXV in 

 larger Port Jackson specimens) ; P, has 15 to 24 segments iii Port Phillip specimens of 

 arm length up to 50 mm. (30 to 32 in larger Port Jackson ones) and P2 is less than half 

 as long with nearly half as many segments; P3 is similar in size to P2 but bears a gonad. 



Remarks [by A.M.C.]. — Mr. A. H. Clark had left his description of the tj-pes of 

 lacertosa from Port Jackson to cover this species. As there is an element of doubt about 

 the identity of lacertosa and incommoda I am inserting here a description based on the 

 type material of incommoda from Port Phillip. 



Description [by A.M.C.]. — The ccntrodorsal is discoidal, ^vith the dorsal pole quite 

 flat and the cirrus sockets crowded round the margin in about two irregular rows. In 

 some specimens the sockets encroach considerably on the dorsal pole, which, as a result, 

 varies in diameter from O.S to 1.6 mm. in 20 specimens, averaging 1.2 mm. 



The cirri are XXIII-XXX in five syntypcs with arm length 25 to c.50 mm., with 

 up to 13 segments except in the largest which may have 14, and up to 8.0 mm. long. 

 The segments are laterally compressed, but dorsoventrally expanded in the distal half 

 particularly. The longer segments have the length to median mdth in lateral \ie\v 

 about 1.5 : 1; they are somewhat constricted in the middle and expanded at the distal 

 ends. The antepenultimate segment is not longer than wide. The opposing spine 

 is well developed and the terminal claw strong and curved, particularly towards its 

 base. 



The arms are 25 to 50 nmi. long in the five syntypes examined. The width at 

 the Ci-st syzygy is 0.7 to 1.1 mm. and the length from the proximal edge of the IBr, 

 to the second syzygy is 5.0 to 6.0 mm. The brachials are slightly flared towards their 

 distal ends. 



P, has 15 to 24 segments which arc slightly flared and spinous at their distal ends. 

 The fourth segment is about twice as long as wide and the following ones become at 

 least twice as long again. The total length is usually little less than the cirrus length, 

 5.5 to 6.0 mm., but in the largest specimen it may exceed the cutus length and measure 

 10 mm. 



Pj is much shorter with S to 12 stouter, more markedly flared and more spiny 

 segments. It is 2.0 to 5.0 mm. long. 



P3 is the first genital pinnule. It has 11 to 13 segments and measures 3.0 to 4.0 

 mm. The segments are still more markedly flared and spinous. 



In some specimens the gonads are considerably expanded and in the females the 

 eggs can be seen through the transparent wall. 



The sacculi are numerous and conspicuous. 



