240 STRATIGRAPHY 



the Antarctic spicule recalls those characteristic of Lelapia, which are figured by 

 Minchin. 



Plate LXXIX. Fig. 6. This spicule may be derived from a Lyssacine Hexac- 

 tinellid, and is of the same nature as those discussed briefly on p. 163 of the Memoir. 



It is, I imagine, quite unconnected with the Archceocyathince present. 



SUINIMARY 



Of the five families of the Archceocyathince alliance (Taylor, op. cit., y>. 105), two 

 are certainly represented — the Archceocyathidce and the Spirocyathidce. The 

 specimens are, in general, too fragmentary for one to detect the presence of tabulae, 

 so that none can be referred to the Coscinocyathidce. 



The aberrant form, figured on Plate LXXIX. Fig. 2, may possibly be allied to 

 the SyrincjocnemidcB (by way of Rhahdocyathiis), but it is doubtful. 



Of sjiecial interest are the three young stages, which I think tend to refute the 

 statement that the immature forms take the form of " Calcareous Gastrulte," as 

 Von Toll supposes. On the other hand, they closely resemble the youthful stages 

 described from South Australia. Two specimens are probably regular species of 

 Archceocyathus ; the third young stage is to be referred to the ProtopharetroB, 

 on the evidence of the irregular nature of the intervallum. 



The specimens of regular Archceocyathus species are of two classes, with straight 

 regular septa, which may be allied provisionally with group IV. (including A. ijizkii, 

 A. Proshurjakou-i, and A. ivirrialpensis) on the chart in the Memoir. 



The majority of the regular specimens, however, belong to group V., with some- 

 what irregular septa and a few dissepiments. They are very jjrobably akin to 

 A. disscpimentcdis and the original type, A. profundus. 



The most interesting of the larger species occur in Slides 123 and 112 of two 

 forms which are certainly Protopharetrce, the former being akin to P. radiata, while 

 the latter is a new species with a peculiar netted inner wall, like that characteristic 

 of A. retezona, which is a species of another genus. I have given this the pro- 

 visional title of P. retezona. 



Two highly irregular specimens may belong to the doubtful species P. duhiosa. 

 They are irregular masses of calcareous laminae, and not improbably are merely 

 rooting attachments. 



A very curious organism, showing only in one section as an annulus formed of a 

 shigle row of oval cells, with mdefinite rays and concentric walls within, is described 

 briefly, but no attempt is made to name it. It is very doubtful if it belongs to the 

 Archceocyathince. 



As in the South Australian specimens, large isolated spicules — not derived from 

 the Archceocyathince — occur. One perfect "tuning-fork" is preserved, and has 

 been photographed. 



