MATERIALS FOK A MONOGRAPH OP THE ASCONS. 579 



In addition 1 was observed (13 s.) of wliich 2 rays lit up ; 1 remained 

 dark. 



Class 2.— G observed, all of which lit up; 3 distinctly {Uj., 15 _/., 

 15 j.) and 3 brilliantly (13 j., Uj., 15 j.)- 

 Embryo B. 

 Class 1. 

 Perfectly dark.— 3 (10 s., 10—12 s., 12 j.)- 

 Faint illumination in centre. — 9 (9 s., 9 — 11 J., 10 5., II j., II j., 



12 i., 11-13 i.[?] 13i.,14i.). 

 Rays faintly illuminated. — 2 (10 j., 11 j.). 

 In addition a triradiate was observed with unequal rays of 11, 9, and 6 n ; 

 the first ray lit up distinctly, the second faintly, the third not at all. 

 Class 2. 

 Centre bright.— 2 (12 j., 15 j.). 

 Illumination fairly bright. — 1 (11 j.). 

 Illumination brilliant.— 6 (8 j., 9— 10 j., 10 j., 10 j., 11 j., 11 j.). 



(4) Falcata, embryo. — 8 spicules examined. 



Perfectly dark.— 3 (2^ s., 3 s., 3 s.). 

 The remaining five were slightly larger, and appeared to have the rays 

 united ; they all lit up distinctly. 



(5) Reticulum, embryo. — All the spicules, even the minutest (rays less 

 than 2 /u), seemed to have their rays united, and lit up brightly. 



Bibliography. 

 (In Chronological Order.) 



1856. LiEBERKiJHN, N.— " Zur Entwickelungsgeschiclite der Spongillen," 



'Arch. f. Anat. u. Physiol.,' 1856, pp. 399— 414, Taf. XV. 



1857. Carter, H. J.— "On the Ultimate Structure of Spongilla, &c.," 



' Ann. Mag. Nat. Hist.' (2), xx, pp. 21—41, pi. i. 



1864. KoLLiKER, A.— 'Icones Histologicse,' Abth. I, Leipzig (Wilhelm 

 Engelmann). 



1864. Schmidt, 0. — ' Spongien des adriatischen Meeres,' i supplement, 



Leipzig, 1864. 



1865. LlEBERKtiflN, N.— " Beitrage zur Anatomic der Kalkspongien," * Arch. 



f. Anat. u. Physiol.,' 1865, pp. 732—748, Taf. xix. 



1870. Schmidt, O. — 'Grundzuge einer Spongien-Fauna des atlantischen 

 Gebietes,' Leipzig, 1870, 



1872. Haeckel, E.— ' Die Kalkschwamme,' Berlin, 1872, 3 vols. 

 1874. (1) Carter, H. J.— "On the Nature of the Seed-like Body of 

 Spongilla, &c.," 'Ann. Mag. Nat. Hist.' (4), xiv, pp. 97—111, pi. x. 



