32 "endeavour" scientific results. 



(Noi Aglaophenia cntciflrZ£s,Kirchenpauer,Abh.Nat. Ver.Hamb., 

 v., 1872, pi. i., fig 8. Bale, Cat. Austr. Hyd. Zooph., 1884, 

 pi. xviii., fig 8.) 



(Not Thecocarpus crucialis, A. Billard, Ann. Sci. Nat., Zool. 

 (9), v., 1907, p. 328, figs. 3, 4.) 



The Aglaophenia crucialis of Lamouroux, an inadequately 

 described species, was supposed by earlier writers (not however 

 bj' De Blaiuville) to be identical with the Plumularia brachiata 

 of Lamarck, and the synonymy was generally accepted until Dr. 

 Billard ascertained by examining the original types that they 

 were distinct species. As two or three Hydroids described in the 

 present paper, as well as A. macrocarpa, previously described by 

 me, are very closely allied to A. crucialis, some refei'ence to that 

 species may be of interest as a preliminary to treating of the 

 forms before us. 



I am not aware that any full description of the typical 

 A. crucialis, or any figure of the structure, has been published. 

 Billard, concluding from the figures and description of 

 A. macrocarpa that it was identical with A. crucialis, contented 

 himself with announcing the synonymy. Ritchie, in his Report 

 on the "Thetis" Collection, gives a photograph of the polypidom, 

 and many details of the structure. Dr. Billard informs me that 

 he thinks from Ritchie's description that his specimens were 

 typical. A form differing somewhat from the others is recorded, 

 but Ritchie considered it only a variety; it is said to be 

 distinguished from the rest by its more dumpy hydrothecoB and 

 internodes. Lamouroux' description only states that the 

 polypidoin is sparsely branched, with the branches in opposite 

 pairs, and that the colour is a light fawn. Ritchie's figure and 

 description indicate that the branches are divaricate at a wide 

 angle and that they may be re-branched to the third degree, 

 while the two series of branches are in planes meeting at a wide 

 angle. The branches arise from the hydrocladiate tube. The 

 hydrothecae are as in A. mitrrocarpa, but the margin varies 

 considerably " the characteristic broad lateral lobe especially 

 exhibiting stages of decrease in size, so that in some specimens 

 it has become obsolete." The corbulas are described as resembling 

 those of A. macrocarpa, but the margins of the leaflets 

 '' frequently rise into very pronounced crests." 



A sketch of one of the best-preserved hydrotheca? of Lamouroux' 

 type, for which I have to thank Dr. Billard, shows the border 

 nearly like that of A. macrocarpa, while the median sarcotheca 

 more resembles that of the form which I have named A. tasmanica. 



