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



(1861). In 1864 Dr. Bowerbank^ (first) defined the genus correctly, assigning to it 

 Spongia oculata, Pallas, as its type species. Schmidt therefore appears to me to be in 

 the wrong when he (Spong. Atlant. Gebiet., p. 32) removes this species to his genus 

 Chalinula, of 1868, and restricts Chalina to species which have the habitus of Euspongia 

 and Cacospongia." ^ 



We have now come to the conclusion that the characters of the genus Chalina should 

 be made to depend rather upon the structure and arrangement of the fibre than uj^on any 

 mere growth form. Thus we should now include in the genus recent species, such as 

 Chalina 7-ectangularis, nobis, which would formerly have come under the genus 

 Acervochalina, and forms like Chalina pergamentacea, Ridley, which have hitherto been 

 assigned to Cladochalina. 



Chalina p)almata, Lamarck, sp. (PI. V. fig. 4). 



1813. Spongia i>almata, Lamarck, Arm. Miis. Hist. Nat. Paris, vol. xx. p. 453. 



Sponge (PL V. fig. 4) of erect habit ; much branched, palmo-digitate ; branches 

 compressed. The single specimen in the collection measures 68 mm. in height by 100 in 

 breadth. Colour in spirit pale j'ellow. Texture soft and spongy, tough and fibrous. 

 Surface fairly even, very slightly hispid ; Avith a reticulate appearance due to the 

 underlying structures appearing through the thin, transparent dermal membrane. The 

 dermal membrane itself has also a very minutely reticulate appearance due to the dermal 

 skeleton fibres. Oscula small, round, irregularly scattered, averaging a little over 1 mm. 

 in diameter. Pores, rounded openings, varying considerably in size, scattered very 

 profusely through the dermal membrane. 



Skeleton. — {a) Dermal; a triangularly and polygonally-meshed reticulation of very thin 

 spiculo-fibre. The fibre contains a very large proportion of horny matter, and has a core 

 of slender oxeote spicules uni- or biserially arranged ; the fibre is also " armed " wdth 

 oxeote spicules stuck through it more or less at right angles, [h) Main ; composed of a 

 rectangularly-meshed reticulation of stouter fibre, containing a very large amount of horny 

 matter, but with a core of slender oxeote spicules arranged in the primary fibres polyserially 

 (not strictly parallel but in a somewhat plumose manner), but in the secondary, crossing 

 fibres, usually only uni- or biserially. 



Spicides. — Small, usually slightly curved oxea, measuring about 0"077 by 0'0024 mm. 



The most characteristic features of this species are its external form and the 

 arrangement of the dermal skeleton. 



We have satisfied ourselves fairly well, by examination of Lamarck's probable tj^^e in 

 the Jardin des Plantes, that ours is the same sjaecies, but as it has never been thoroughly 

 described, we give a full description. Lamarck's Spongia pahnata is not to be confused 



1 Mon. Brit. Spong., vol. i. p. 208. 



2 Ridley, Zool. Coll. H.M.S. " Alert," Brit. Mus., 1884, p. 393 ; Cf. also Vosmaer, Broim's Klass. u. Ordnung. 

 des Thierreiohs, Porifera, pp. 211, 341. 



