30 THE VOYAGE OF H.M.S. CHALLENGER. 



possess their own skeleton, the spicules constituting their support being of quite a different 

 form from all other spicules of the sponge. I think this peculiarity is important enough 

 to be regarded as a generic character, and as there are in the Monograph of Prof. Hseckel 

 nine Leuconidse described under the name of Leucandra prior to our Leucandra cucvmis, 

 three of them being in addition quite new forms, I think it preferable to unite tempo- 

 rardy the forms with evident subdermal cavities under a new name. I propose the name 

 Pericharax tdl we receive more detaded information as to the systematic position of 

 Leucandra caminus, H., Leucandra lunulata, H, and Leucandra crambessa, H. 



The Famdy Teichonidae consists at present of only two genera, of which the first is, — 



Teichonella, Carter. 1 



It contains two species, prolifera and labyrinthica, and Mr. Carter characterises it 

 as follows : — " Vallate or foliate, without cloaca. Vents numerous, confined to the margin 

 or general on one side of the lamina only ; naked." This definition, compared with that 

 given by Bowerbank 2 to his genus Leucogypsia, renders it evident that the expression 

 "without cloaca" is used by Mr. Carter in a somewhat different sense. The Australian 

 specimen of my Leucondra dura (PL II. fig. 3) would have been referred by Bowerbank 

 to the genus Leucogypsia. Like Leucogypsia gossei, Bwk., it possesses no evident cloaca ; 

 still it does not belong to the Teichonidae, 3 the main character of this Famdy consisting in 

 the differentiation of the outer surface into two planes, one bearing oscula, the other 

 pores exclusively. But whether the oscula in Teichonidae are homologous with the oscula 

 of Hseckel or the oscula of Bowerbank, it is difficult to say ; the question can be decided 

 only by means of embryological observations. Amongst the Challenger Calcarea I have 

 a specimen (Leuconia typica, var. massa), provided with a low and comparatively 

 broad, calyciform inner cavity. It may be that the oscular plane of our Teichonidae 

 is homologous with the surface of this calyciform cavity, and is nothing but the 

 gastric surface of a Syconid or Leuconid, modified with respect to its form and position. 

 It may also be that the Teichonidae are allied to the forms like my Leuconia dura, i.e., 

 that a Teichonid is, from a morphological point of view, a colony with dislocated oscula 

 and pores. It must be noticed that, in view of F. E. Schulze's statements as to the 

 ontogeny of Sycandra raphanus, this latter supposition is more plausible. At any 

 rate the peculiarity in question is to be considered as a famdy character, the more so 

 as there is no possibdity of putting my Eilhardia in the genus Teichonella as a species, 

 the differences in the spiculation and exterior form being too considerable. The diagnosis 

 of this genus will be as follows : — 



1 Ann. and Mag. Nat. Hist., ser. 5, vol. ii. p. 39, 1878. 2 Brit. Spongiad., vol. i. p. 165, 1864. 



3 Mr. Carter (loc. cit., p. 35) calls the Family " Teichonia" and " Teichonellida?" indifferently. In order to render 

 it uniform with the names Asconida?, Syconidse, and Leuconidse, I propose to call it Teichonidse. 



