PORIFERA. III. 



II 7 



1907. H. rufa Kirkpatr. Ann. Mag. Nat. Hist. 7, XX, 274, and 1909, Nat. Antarct. Exp. IV, PI. XXII, 

 fig. 5, PI. XXVI, figs. 3 a — e. (Hymcraphia). 

 H. interjecta mihi 

 H. conjungens mihi 

 H. tenuisclera mihi 

 H. duplicata mihi. 



I do not see the slightest reason why H. minima Tops, and H. rufa Kirkpatr., both placed by 

 the authors in Hymcraphia, should not belong to Hymenancora. 



1. H. interjecta n. sp. 



PI. XI, Fig. 4. 



Jncrusting; surface slightly hispid. Spicula: megasclcra; tlic skeletal spicules acanthostyli without 

 a real head-swelling, spined in the whole length, they are divided into two groups, large o-j? — 0-47 """, 

 small 0-/4—0-16""",- the dermal spicules tylota or subfylota o-jo—o-j?"""; microsclera two forms, ancorce 

 spatulifcra with three teeth, 0-025 — 0-045""", sigmata 0-06 — 0-128""". 



Of this species we have two specimens; one grows on a dead branch of an Oculina together 

 with H. procumbeiis and specimens of Tedania, Eurypon and Latrunculia : the other specimen, which 

 is very small, grows on a pebble. The largest specimen is extended along the Oc7ilina-brs.nch. and is 

 therefore of a lengthy shape and has a greatest extent of 22 mm ; it is exceedingly thin. The colour 

 (in spirit) is greyish or brownish. The surface is in the present state of the sponge slightly hispid. 

 Abont the dermal membrane, pores and oscula I can say nothing. 



The skeleton. The dermal skeleton seems to consist of bundles and scattered spicules. The 

 main skeleton is, so far as I could observe, constructed in the ordinary way of vertical acanthostyli 

 piaced on the substratum, but the styli are somewhat scattered and the dermal skeleton is therefore 

 the most developed part of the whole skeleton. 



Spicula: a. Megasclera. 1. The skeletal spicules are acanthostyli which are somewhat 

 distinctly divided into two groups. The large styli are straight or generally somewhat curved near 

 the base; the base is a little thickened, but there is no head-swelling present, and they taper into a 

 long and fine apex; the styli are spined in their whole length, but the spines are only at the base 

 of larger size, they decrease in size outwards, and the shaft and apex are only gritty; the larger 

 spines at the base are generally curved upwards in a somewhat characteristic way. The small styli 

 are principally of the same shape as the large, but they are often straight, and the spines are relatively 

 larger, the head also is still less developed than in the large. The length of the large styli is 0-37 — 

 047 mm with a diameter at the base of 0-020— 0-023 mm . The small styli have a length of 0-14 — o-i6 mm 

 and a diameter at the base of 0-020 mm . 2. The dermal spicules may best be termed tylota; they 

 are straight or very slightly curved and somewhat robust, the end-swellings are very small but how- 

 ever always perceptible. The length is 0-30— 0-47""", and the diameter of the shaft 0-007— o-oio mm . 

 b. Microsclera are of two forms, ancoroe spatuliferse and sigmata. 1. The an corse have a curved shaft 

 and three elliptical teeth at each end, but the most remarkable feature is, that they have only very 



