TWO NEW SPONGILL-E FROM LAKE TANGANYIKA. 487 



10. ScnuLZE, F. E., und LEXDENfELD, R. V.—" Ueber die Bezeichnuug der 

 Spongiennodelii," ' Abhandl. d. k. preuss. Akad. d. wiss. Berlin,' 

 Abb. ii, S. 1, pp. 1—35, 1889. 



U. SoLLAS, W. J.— "Plectronella papillosa," 'Ann. Mag. Nat. Hist.' 

 (5), iii, p. 17, 1879. 



12. TopsENT, E. — "Contribution a I'etude des Clionedes," 'Arch. Zool. 



Exper. et Gen.' (2), v bis., mem. iv, 1890. 



13. Weltner, W. S. — " Spongilliden Studien," iii, 'Arcb. f. Naturgesch.,' 



vol. Ixi, 1, p. 114, 1895. 



EXPLANATION OF PLATES 37 and 38, 



Illustrating Mr. Richard Evans' paper " Ou Two New 

 Species of Spongilla from Lake Tanganyika.'' 



The figs. 1— Son Plates 37 and 38 refer to Spongilla moorei, figs. 9 and 

 10 on Plate 38 to Spongilla tanganyikaj, and fig. 11 to Potaraolepis from 

 the mud of Lake Tanganyika. 



PLATE 37. 



Fig. 1. — (x 1.) Spongilla moorei growing on a niolluscan shell. 



YiG, 2.—{a—e and e—m X 300 ; a', h\ c', and d X 750.) A number of 

 irregularly shaped spicules showing both the variety and the irregularity of 

 form which they present. The spicules a , V, c' represent a, b, and c on a 

 larger scale of magnification, and together with the spicule d show the relation 

 which exists between the axial threads in these compound spicules. 



Fis. 3. — ( X 300.) Amphioxea and amphitornota without swelling, 

 a, b, and I. Straight amphioxea. c—k. Curved amphitornota. j, k, and I 

 are possibly microscleres, or they may be young megascleres. 



j^ig, 4.— (X 300.) Amphioxea and amphitornota with swellings, a. 

 Straight ampliioxea with four swellings, b—l. Curved amphitornota with a 

 variable number of swellings from one to five, d shows the swellings asym- 

 metrically arranged, h—n. Either microscleres or young megascleres with 

 one swelling. 



Fig. 5.— (X 750.) Masses of silica found in Spongilla moorei, 

 varying both in size and shape. 



