TETRALASMIS HIRSUTUS. _Cuvier._ Regne Animal, vol. iii, 1830. ANATIFA HIRSUTA. _Quoy_ et _Gaimard_. Voyage de l’Astrolabe, Pl. xciii, figæ. 7-10, 1834. _I. (Herm.), valvis et pedunculi spinis sub-flavis: basali tergorum angulo, introrsùm spectanti, hebete, quia margo carinalis inferior longiùs quam margo scutalis prominet._ _Hermaph._--Valves and spines on the peduncle yellowish: basal angle of the terga, viewed internally, blunt, owing to the lower carinal margin being more protuberant than the scutal margin. Caudal appendages four times as long as the pedicels of the sixth cirrus: rami of the first cirrus unequal in length by about six segments. _Complemental Male_, with a notched crest on the dorsal surface, forming a rudiment of a capitulum: maxillæ well furnished with spines. Kangaroo Island, South Australia (Mus. Brit., given by Cuvier to Leach); Adelaide, South Australia (Mus. Stutchbury); King George’s Sound, Voyage of Astrolabe; New South Wales, attached to a mass of the Galeolaria decumbens, (Mus. Hancock). HERMAPHRODITE. All the external parts so closely resemble those of _I. Cumingii_, that it would be superfluous to describe more than the few points of difference. The horny substance of both scuta and terga is uniformly yellow; though in dryed specimens, from the underlying corium being seen through the valves, these generally have a tinge of blue. The _Scuta_, viewed internally, are less elongated transversely; they have their basal margins slightly more hollowed out, and the fold on the upper free and horn-like portion rather deeper. The _Terga_, viewed internally, have the apex of the growing or corium-covered surface higher relatively to the scuta than in _I. Cumingii_; and the basal angle is much broader, owing to the lower carinal margin being much more protuberant than the scutal margin. The spines on the peduncle are all yellowish-brown, and are rather longer than in _I. Cumingii_. I observed in three or four specimens, that the lowest part of the peduncle had become _internally_ filled up with the usual, brown, transparent, laminated cement, cone within cone, so that this lower part was rendered rigid and stick-like; this latter effect, I apprehend, is the object gained by the formation of cement within the peduncle, of which I have not observed any other instance. The entire length of the largest specimen was one inch; some other specimens were only half this size.