JOURNAL OF MICROSCOPICAL SCIENCE. 



EXPLANATION OF PLATES V, VI, & VII, 



Illustrating Mr. Peck^s memoir on the Structure of the 

 Laaiellibranch^s Gill. 



The letters in all the figures have the same signification. 

 Larger Parts. 



L. Outer lamella. 



/ L. Inner lamella. 



ilj. Interlamellar junction. 



F. Gill-filament (not in figure 18, see below). 



Us. Interlamellar space. 



Tr. Transverse elements, or interfilamentar junctions. 



sfe. (In fig. 17) Surface of the subfilamentar outgrowth or internal 

 surface of the lamella. 



V. Large vertical vessel. 



v' . Small horizontal or transverse vessel. 



IF. Window or stoma of a water-passage. 



s. Outer surface of a section. 



e s. Inner surface of a section. 



/. Lumen of a vessel. 

 Histological Detail. 



e. Epithelium. 



fe. Frontal epithelium of the gill-filaments. 

 Ife., Ife', Ife". Latero-frontal epithelium of the first or second order 



(gill-filament). 

 le, le' . Lateral epithelium of the gill-filaments. 

 lac. Lacunar tissue (primitive mesoblastic or mucous tissue). 

 ch. Chitinous deposit representing part of the chitinous tube of the 



primitive Lamellibranch gill-filament. 

 chc ami nch. Corpuscles embedded in the above chitinous deposit. 

 cr. Chitinous rods differentiated in the chitinous deposit [ch). 

 tr f. Fibrous tissue of the transverse interfilamentar junctions. 

 be. Blood-corpuscle. 

 yg. Yellow granular material accumulated in the subfilamentar 



lacunar tissue of Anodon, and destined for the nutrition of the 



Glochidian embryos. 

 pig. Pigmented corpuscles of the lacunar tissue. 

 J)'. Elastic or muscular fibrous elements in the lacunar tissue. 



f. (In fig. IS) Trabecula of the lacunar tissue. 



n. Nucleus surrounded by granular protoplasm (lacunar tissue). 

 pe. Peripheral expansion and attachment of a trabecula. 



PLATE v.— Anodon. 



Fig. \. — Transverse section of a portion of an outer gill-plate, with 

 swollen lacuna-bearing interlamellar junctions. Low power. 



Fic. 2. — Transverse section of a portion of .in outer gill-plate, with 

 solid interlamellar junctions and large vertical vessels. Low power. 



Fi(i. 3. Transverse section of a portion of an inner gill-plate, showing 

 curvature of the outer lamella, relatively small depth of inner lamella, 

 and vertical vessels in the inter lamellar junctions. Low power. 



Fi(i. 4. Transverse section of a portion of outer gill-plate, distended 

 with Glochidian embryos (schematic). 



