350 BALANIDiE. 



Cirri : the first pair has one ramus nearly twice as long as the other. 

 The three posterior cirri are elongated, and each segment supports five 

 or six pairs of long spines, with a few minute intermediate bristles. 



- . 



Elminius modestus. PL 12, fie. 1 a — 1 e. 



&' 



Shell folded longitudinally, greenish or white: radii of 

 moderate breadth, smooth edged: scutum without an ad- 

 ductor ridge : tergum narrow, with the spur confluent with the 

 basi-scutal angle. 



Hab. — New South Wales ; Van Diemen's Land ; New Zealand ; very com- 

 monly attached to littoral shells and rocks ; associated with Balanus trigomis 

 and vestitus; Mus. ]3rit., Cuming, Stutchbury, Darwin. 



General Appearance. — Shell conical, generally rather steep, occa- 

 sionally depressed: walls longitudinally folded, sometimes very deeply, 

 sometimes only to a slight degree : colour dull greenish or white. 

 Radii of moderate width, with their summits very oblique, smooth and 

 slightly arched : alae much exposed, with their summits less oblique 

 than those of the radii : the portion added to the aloe during the diame- 

 tric growth differs much in appearance from the other portion. The 

 scuta have the growth ridges but little prominent ; they are crossed by 

 a faint longitudinal band of gray. The largest specimen out of the 

 many which I have seen, was under '4 of an inch in basal diameter. 



Scuta, destitute of an adductor ridge and of crests for the depressor 

 muscles : the articular ridge is moderate ; but the articular furrow is 

 rather wide : the internal occludent margin is much thickened. The 

 Terga are narrow and small ; they are somewhat variable in shape, 

 caused by the degree to which the basal margin is hollowed out (fig. 1 c 

 — 1 e), and likewise by the extent to which the upper end of the valve 

 has been worn away. No spur is apparent, for it is confluent with the 

 basi-scutal angle of the valve. The articular ridge is very prominent, 

 and runs down to the basi-scutal angle; and as the valve in this part is 

 extremely narrow, with the spur not developed, it here assumes a chan- 

 nelled structure. The basi-carinal corner of the valve is furnished 

 with rather feeble crests for the depressor muscles, and in those varie- 

 ties in which, the basal margin is much hollowed out, this part is 

 remarkably narrow. 



Structure of the Parietes and Radii. — The internal basal edges of 

 the parietes and the sutural edges of the radii and aire, are all smooth. 

 The lower edge of the sheath depends freely. In the green varieties 

 the colour is most distinct on the internal surface of the shell. The 

 four compartments separate very easily when the shell has been ill pre- 

 served in spirits, or after a very short immersion in caustic potash. 



Mouth, as in E. Kmgii, excepting that there are only three teeth 

 on each side of the notch (which is deeper) on the labrum. The 



