558 Prof. R. Burckhardt on the 



Literature cited. 



Carter, H. J. (1858.) — "On Fecundation in Eudorina elegans and 



Crt/ptoglena," Ann. & Mag. Nat. Hist. ser. 3, vol. ii. pp. 237-253, 



pi. viii. 

 . (1871.) — "Note on a Freshwater Species of Ceratium from the 



Lake of Nynee (Naini) Tal in Kumaon," Ann. & Mag. Nat. Hist. 



ser. 4, vol. vii. pp. 229, 230. 

 Garman, H. (1890.) — " A Preliminary Report on the Animals of the 



Mississippi Bottoms nearQuincy, Illinois, in August 1888," Part I., 



Bull. Bl. State Lab. Nat. Hist. vol. iii. pp. 123-184. 

 Kofoid, C. A. (1898.) — " Plankton Studies, II. On Pleodorina illiuois- 



ensis, a new Species from the Plankton of the Illinois River," Bull. 



111. State Lab. Nat. Hist. vol. v. pp. 273-293, pis. xxxvi., xxxvii. 

 Schroder, B. (1898.) — " Dangeardia, ein neues Chytridineen Genus 



auf Pundorina morum, Bory," Ber. d. deutsch. Bot. Gesellsch. 



Jahrg. 1898, Bd. xvi. pp. 314-321, Taf. xx. 



EXPLANATION OF PLATE VII.* 



Abbreviations. 



A. Anterior pole. P. Posterior pole. 



c.v. Contractile vacuole. p. Outer pellicle of protoplasm. 



f. Flagellum. pr. Knob-shaped mass of proto- 



m. Matrix. plasm. 



n. Nucleus. pyr. Pyrenoid. 



ncl. Nucleolus. s.sh. Secondary sheath. 

 p.sk. Outer or primary sheath. st. Stigma. 



Fig. 1. Platydorina cavdata, face view of 32-cell colony, X 550. 

 Fig. 2. Face view of 16-cell colony, X 628. 

 fig. 3. Edge view of 32-cell colony, X 350. 

 Fig. 4. Lateral view of one of the marginal cells, x 1400. 

 Fig. 5, a-e. Outline of the posterior ends of several deformed colonies, 

 X 280. 



LXXIT. — On the Luminous Organs of Selachian Fishes. By 

 Eud. Burckhardt, Nat. Hist. Mus., S. Kensington. 



In the ' Zeitschrift fur wissenschaftliche Zoologie,' vol. Ixvi. 

 1899, Johann, at the instigation and under the guidance of 

 Prof. Blochniann, of Tubingen, published a paper entitled 

 " Ueber eigenthiimliche epitheliale Gebilde (Leuchtorgane) 

 bei Spinax niger" in which are given the results of some 

 researches he made in this subject. 



In this paper he describes some very minute organs with 



* Figures drawn by C. A. Kofoid and inked by Miss L. M. Hart. 



