| OCR Text |
Show 1886.] POSITION A N D CLASSIFICATION OF SPONGES. 561 The following six forms can be distinguished :- A. Regularia. The rays radiating from one point. 1. Oxyaster. With long, slender, pointed rays (e. g. Stelletta). = st, Vosmaer. 2. Euaster. With stout, pointed, conic rays (e. g. Chondrilla).=gl. st, Vosmaer. 3. Spheraster. The rays coalesce to form a solid ball (e.g. Geodia).=gl, Vosmaer. B. Irregularia. The centre extends to form a line which may be curved, circular, ring-shaped, or spiral. 4. Spiraster. A stout spiral with thick spines attached (e. g. Raphyrus). = st2, Vosmaer. When spines terminal, Amphiaster. 5. Corona. A spined ring (e.g. Suberocorona) (?). 6. Spirula. A spiral without spines (e. g. Spiretta). These anaxon spicules never form part of the supporting skeleton, but are invariably flesh-spicules (Microsclera). 2. Monaxonia. With one straight or curved axis, sometimes with lamellar outgrowths. A. Supporting Spicules (Megasclera). 1. Strongylus. A cylindrical rod rounded at each end (e.g. Uruguay a). = tr2, Vosmaer. 2. Oxystrongylus. A cylindrical rod abruptly pointed at each end (e.g. Pachychalina). 3. Oxy us. A gradually pointed, spindle-shaped spicule (e. g. Spongilla). = ac, ac, and ac2, Vosmaer. Diact, F. E. Schulze. 4. Tylotus. A cylindrical rod with a knob at each end (e. g. Crella). = tr02, Vosmaer. 5. Tylostylus. A cylindrical rod more or less pointed at one end and knobbed at the other (e. g. Suberites). = tr° ac, Vosmaer. Without knob, Stylus. PROC. ZOOL. Soc-1886, No. XXXVII. 37 |
