JOURNAL OF MICROSCOPICAL SCIENCE. 



DESCRIPTION OF PLATES XI & XII. 



PLATE XI, 



Illustrating Mr. Archer's paper on the Occurrence of 

 Zoospores in the Family Desniidiacese. 



*%• 



1, 2, 3, 4. — Doeidium Ehrenbergii, with lateral projections iii different stages 

 of development. 



5. — Parasitic growth (Pythium) upon Closlerium lunula. 



6. — Mycelioid growth within Closlerium lu/iula, R. 



7. — Arthrodesmtts Incus. 



8. — Cosmarium Portianum ; front view. 



( J. — „ „ end view. 



10. — Tanthidium Smithii ; front view. 

 11. — „ „ side view. 



12. — ,, „ end view. 



PLATE XII, 



Illustrating Professor Huxley's paper on the Structure of 

 the Mouth and Pharynx of the Scorpion. 



Fig. 



1. — Longitudinal vertical section of the cephalo-thorax of a Scorpion, show- 

 ing the pharynx, oesophagus, nervous centres, and the large eyes, in 

 their natural relations. 



2. — Dorsal view of the cephalo-thorax of a Scorpion, opened and dissected, 

 so as to show the apodemata, and the anterior portion of the ali- 

 mentary canal, with the pharyngeal muscles. 



3. — The chitinous lining of the anterior part of the alimentary canal, the 

 integument of the labrum, and the basal processes of the first maxilla. 



4. — The chitinous lining of the pharyngeal sac, viewed from above. 



5. — A transverse section of the same, taken along the line x y (fig. 3). 



6. — The region of the pharyngeal sac near the commencement of the 

 oesophagus. 



The letters have the same significations throughout : — a, mouth ; b, labrum; 

 c, pharynx ; d, oesophagus ; e, salivary duct ; /, diaphragm ; g, eye 

 ami ocular nerve ; //, subcesophageal ganglion ; ?', antenna ; /-, maxilla ; 

 /, mandible j m, apodeme; «, pharyngeal mu cles j o, sub-oral trans- 

 verse thickening of (he chitinous integument ; />, valve (P) of the 

 pharynx ; ry, fine along which the section in fig. 5 is taken. 



