44 " ENDBAVODB " SCIENTIFIC RESULTS. 



The hydrothecss arc of the same type, making however a some- 

 what wider angle with the supporting internode. The median 

 tooth is longer and thicker, the lateral teeth larger and more in 

 the middle; the two angular lobes behind the lateral sareotheca? 

 as in A. billardi. The aperture of the anterior sarcotheca is 

 oblique. The lateral sarcotheca? are only slightly divergent 

 laterally, and they seem to differ somewhat from the other forms, 

 especially iu a slight thickening at the foot of the front wall. 

 The intrathecal fold is excessively feeble, but the thickening at 

 its base, as also at the base of the lateral sarcotheca 3 , is very 

 pronounced, owing to its deep colour, nevertheless the annular 

 septal ridges which usually originate at these points are 

 generally absent, though occasionally slightly indicated, especially 

 in the less mature hydrocladia. 



The first specimen obtained was without the gonosome, but a 

 second example, collected in the autumn, bore numerous 

 corbula?, and others received still more recently from the 

 Australian Museum, show that there is in this species a distinc- 

 tion between the sexes similar in character to that which exists 

 in the last two. The female corbula? have the superior free 

 lobes very robust, but not nearly so large as in those of 

 A. billardi and A. tasmanica ; they do not form large over- 

 lapping crests, but mostly rise only about as high as the upper 

 surface of the corbula. The lateral spurs are long and stout, but 

 with fewer sarcotheca? than those of the other species, where they 

 are set closer together. The end of the gonocladium forms a 

 stout prolongation curving up round the end of the corbula like 

 the prow of a boat. The male corbula? have the protective 

 structures less developed, but they are also distinguished, in all 

 the specimens examined, by the leaflets becoming so much 

 reduced at the distal end of the corbula that the latter narrows 

 ;i \\ ay to the point so as to have a caudate aspect to the naked eye. 

 For most of its length the corbula is closed, though here and there 

 interstices may be seen where the leaves fail to meet ; towards the 

 end however, the nmch abbreviated leaflets are separate. The 

 fragmentary appearance of the corbula at this part at first seemed 

 to me the result of decay, but finding it general and apparently 

 limited to the male corbuhe, I am now inclined to regard it as 

 normal, more especially as the few corbula? wbich I have seen of 

 .1. macrocarpa, the most nearly allied species, agree in this 

 particular.* Between the male corbula? of these two species I 



*A similar condition of the open male corbula of A. diegen.tis is 

 figured by Torrey and Ann Martin in their paper on " Sexual Dimorp- 

 hism in Aglaophenia," University of California Publications, Zoology, 

 vol. 3, p. 43, fig. 2. 



