EXPLANATION OF PLATES VI, VII, VIII, IX, X, XI, XII- continued. 



EiG. 7. — Transverse section of the coxal gland of a young specimen of 

 Scorpio (Euscorpius) Italicus, Roes. Magnified about eighty diameters. 

 N. Core or medullary tissue, cbv. Axial blood-vessel traversing the core 

 of medullary tissue. K. Lumen of the cseca of the gland, o. Inter-csecal 

 space or channels (partly occupied by very delicate connective tissue, see 

 Fig. 5, Plate XII). /. Gland-epithelium. F. Caeca of the gastric gland. 

 X. Membranous connective tissue enclosing the gland. _y. Blood-space. 



Fig. 8. — Section of a portion of the antennary coxal glaud (green-gland) 

 of Palaemon. K. Lumen of the gland-caeca. I. Gland-epithelium, m. Inter- 

 caecal connective tissue. Magnified 820 diameters. 



PLATE IX. 



Fig. 1. — Section of a portion of the entosternite of Limulus, taken from 

 the central region, deeply. It shows the development in this part of the 

 entosiernite's tissue of a well-defined system of branched anastomotic fibres 

 (presumably elastic) which traverse the homogeneous matrix, and gives this 

 variety of the tissue a close resemblance to the yellow elastic cartilage of 

 Mammalia, a. Cell-nuclei. b. Branched elastic fibres, c. Homogeneous 

 matrix. Magnified 300 diameters. 



Fig. 2. — Section of a portion of one of the tendinous lateral rods of the 

 entosternite of Limulus (A. L. £. of Plate VI, Figs. 1 and 2), taken parallel 

 with the length of the rod in order to show the regular arrangement of the 

 cells in rows, resembling white fibrous cartilage, a. cell-nuclei, c. Matrix. 

 Magnified 300 diameters. 



Fig. 3. — Fragment of a membranous ligament of the heart of Limulus, stained 

 and magnified 300 diameters. Above the dotted line x y, the surface of the 

 membrane is in focus in order to show the closely set covering of protoplasmic 

 corpuscles, indicated by their oblong well-stained nuclei {a). Behind the line 

 xy, a deeper stratum is represented, consisting of undulating and matted 

 fibres. This is representative of the structure of " membranous connective 

 tissue " in Arachnida. 



Fig. 4. — Portion of a tendon of the branchio-thoracic muscle of Limulus, 

 being the connective-tissue investment of one of the hollow tegumentary 

 ingrowths corresponding to the parabranchial stigmata. The specimen is 

 selected to show the fine parallel fibrillation of the matrix and the absence 

 over large areas of any protoplasmic cells, a. Cell-nuclei. Magnified 300 

 diameters. 



PLATE X. 



Fig. 1. — Section through lacunar tissue (left side of the drawing) and the 

 cortical substance of a lobe of the coxal gland (right side) of Limulus. 

 Magnified 275 diameters, a. Nuclei of the cells of the lacunar connective 



