| OCR Text |
Show 1886.] POSITION AND CLASSIFICATION OF SPONGES. 563 developed and branched or covered with disks or scales. The opposite ray smooth or absent. The other four equal (tangential). 7. Scopula?. Fork- or broom-shaped spicules consisting of a long shaft traversed by an axial rod, to the distal end of which some, generally four, slender anaxial rods are attached. 8. Amphidisc. A rod with an umbrella-shaped disk at each end. 9. TJncinatce. A rod with recurved hooks throughout its entire length. 10. Clavulce. A rod pointed at one end and bearing a knob or disk at the other. 4. Tetraxonia. With four axes radiating from one point. The ends of the spicules lie in the corners of a square pyramid and their derivatives. A. Tetractina. B. Triactina. C. Diactina. With four rays. With three rays. With two rays. D. Monactina. With one ray. For the reasons given above, I shall abstain from describing the Tetraxonian spicules in detail. I will, however, mention the terms for spicules employed by Sollas in his preliminary report (1453). These, alphabetically arranged, are the following :- Acerate (Monaxon). Acerella (Monaxon ?). Amphiaster (?). Ampbiastrella (Spirastrella ?). #Amphitetrad. *Anchors. Antbaster (?). Arculus (?). #Bifurcated Forks. Caltbrops (?). ^Candelabra. Cbiaster (?). Cylindrical spicules (Monaxonia ?). Echinella (?). Ectaster (?). Erdaster (?). *Forks. tfForks with trifurcate arms. *Fusiform Acerates (Monaxonia). Globate (Scleraster). Globules (?). Hispidating Acerate (Monaxonia). #One-pronged (unicellate) Forks. #Porrectate Forks. Pycnaster (?). ^Radical Anchors. Sigmella (?). ttSonial Anchor. *Somatic Anchor. Spinispirulae (Spirastrella). Spirula; (Spirulse). Stellate (?). *Tetrad. #Triona. Tricbite Acerates (Monaxonia). #Trichite Forks. *Trifid Forks. *Two-pronged (dicellate) Forks. The names marked * presumedly apply to Tetraxon spicules. The others probably belong to different groups. 37* |
