38 "endeavour" scientific RESULTS. 



forwards from the distal edge of each rib just above its origin, 

 bearing two series of sarcothecee (up to six or seven on each side) 

 but no hydrothecee. 



Colour. — Light fawn. 



Two or three specimens were obtained, the largest being about 

 a foot in height, and dividing into two main stems, one of which 

 is broken off. It is about '■'< mm. thick near the, base and 2 mm. 

 above the division. The existing stem is bare for about half its 

 height to the lowest remaining branches, where the hydrocladia 

 also commence. There is first a single branch, then a pair, 

 about 18 mm, higher a second pair, and a third pair about 

 50 mm. above the second. One of the branches of the second 

 pair is longer than the others (about 110 mm.); about 25 mm. 

 u p it bears a very small branch, 12 mm. higher a larger 

 one (on the same side), then two opposite pairs at pretty 

 regular intervals. All the branches face in the same direction 

 and commence with several internodes bearing median sarcothecee 

 only. The hydrocladia often attain 20 to 25 mm. in length. 



The hydrothecae are very similar to those of ^4. billardi, 

 l)ii t differ in their proportions, as described under that species. 

 The mesial sarcoheca is closely adnate throughout, not pro- 

 jecting as in all the allied forms. 



Only the female corbulaa were seen. They resemble those of 

 A. billardi but are usually more luxuriantly developed, the 

 superior crests, as well as the lateral spurs, being larger, and 

 supplied with a greater number of sarcothecee. 



Loc. — Oyster Bay, Tasmania, 20 fathoms. 



I now proceed to summarize the differences and resemblances 

 between the three forms which 1 have examined, namely 

 A. macrocarpa, A. tasmanica and A. billardi, with, so far as I 

 can ascertain, the corresponding particulars for A. crucialis. 



As to ramification, the general type is the same in all these 

 species, the branches being mostly in pairs and practically 

 opposite. In reality each pair springs from two successive 

 internodes of the hydrocladiate tube. Too much reliance must 

 not be placed on the paired condition, as unpaired branches are 

 often found. In well-grown specimens the lower pari of the 

 stem is denuded of both branches and hydrocladia. 



In .1. crucialis the hydrocaulus seems, considering the size of 

 the polypidom, rather slender, at least in the distal portion, which 

 retains the hydrocladia. The pairs of branches are widely 



