SPONGES. -HALLMAXxN. , -- 



labelled ''Kchi>i<nii'i}ia iiicnistaiis Carter type,'' and ''Pliinio- 

 halichondria niammillata. Carter" respectively. These do not 

 satisfactorily corroborate Dendy's assertion of the svnonyniy 

 of the two names, since the latter slide show s a skeletal struc- 

 ture rather resembling that of the \ar. levis, and chelae A'arv- 

 ing from 13 to 26^1 in length; whilst in the former the 

 structure is much looser — somewhat similar to that of the var. 

 digitata — and the chela? are only u to 2J f( long. Without 

 wishing to attach any great importance to this discrepanc} , I 

 simply point to the possibility of a varietal difference between 

 the sponges of Carter's two species. The point can only be 

 settled by a re-examination of the original specimens. In 

 view of the existence of so many distinct but closely allied 

 varietal forms of this species, ^ it is necessary to proceed 

 cautiously in introducing synonymy ; unless a complete con- 

 necting series between two forms is known to exist, it is far 

 better — because less liable to lead to confusion — to treat them 

 as distinct varieties, each with a distinguishing name. -Ac- 

 cordingly I would recommend that the PJiimohalichondria 

 niammillata of the "Challenger" Report be still considered a 

 variety distinct from the Echiuonema incrustans. Carter. In 

 their description of this variety, Ridley and Dendy state that 

 the dermal skeleton is a reticulation made up exclusively of 

 acanthostyles ; they also refer to their examination of a small 

 piece of the type-specimen of Carter's Phimolialichoiidria 

 mammillata and mention concerning it that the dermal acan- 

 thostyles are intermingled with smooth oxea and not reticu- 

 lately arranged. These differences in the dermal skeletons of 

 the two sponges, thev allowed, might verv well prove 

 distinctive ; but the other characters showed so close a corres- 

 pondence that, under the circumstances, taking into account 

 the small size of the piece examined, and the possibility of some 

 amount of variation with age they did not consider it advisable 

 to distinguish the two by the introduction of a new name. Of 

 the varieties whose descriptions follow there is onlv one, viz., 

 digitata, in which the oxea have been found to enter into the 

 formation of the dermal skeleton ; accordingly, there is good 

 reason to believe that the presence or the absence of dermally 

 situated oxea may be a characteristic which is constant for 

 any given variety. The variety from Oyster Bay to which I 



1 In addition to the varieties described in this Report, I have before 

 me three others which are unriuestionably quite distinct. Owing to the 

 scantiness of the material and its unsuitable state of preservation, I do 

 not venture to describe them. One is probably identical with a British 

 Museum sponge bearing the manuscript name " Clnthi-issa membraiiacea, 

 Lendenfeld." Another bears a label in Lendenfeld's writing with the 

 name, "Clathrissa arbn.icuhi," a species to which it bears some external 

 resemblance. The third is a ramose sponge of irregular growth with the 

 oscula situated singly at the e-^tremities of branches. 



