22 PHYSIOLOGICAL SERIES. 



the canals minute tubes, like those of dentine, radiate for a 

 short distance into the matrix. These tubes are most 

 marked in Ilistiophorus. 



A. 73. Skeleton of a young Fistularia ser^ata, and skull of an 

 adult. The bones in this fish, as also in all Pleuronectidse 

 (Flat-fishes), are traversed by numerous Haversian canals 

 from which and from the surface of the bone numerous 

 dentine-like tubules pass into the matrix. A drawing 

 shows the structure. 



A. 74. Skeleton of Trout (Salmo fario] and Grayling ( Thymallus 

 vulyaris). As in all Salmonidse, cells lodged in lacunse 

 are present but are not provided with intercommunicating 

 canaliculi. The structure is shown in a drawing. 



A. 75. Skeleton of Herring (Clupea harengus) and Carp (Cy- 

 prinus carpi o) . A drawing shows the well-developed lacuna. 1 

 and canaliculi present in all Clupeidse and Cyprinidge. 



REPTILES = REPTILIA. 



A. 76. The carapace of a very young Turtle (Clielone mydas), 

 showing the state of ossification, which is continued from 

 the margins of the ribs, at this period quite distinct from 

 each other, into a pre-existing ossifiable basis of the costal 

 plates, until these plates become joined by indented sutures 

 similar to those of the cranium. 0. C. 131. Hunterian. 

 Goette, Zeitschr. wiss. Zool., Bd. Ixvi. 1899, p. 407. 



A. 76 a. Longitudinal section of the left humerus of a Turtle 

 (Chelone mydas}. There are no epiphyses. The articular 

 cartilage is 4 mm. thick, and has the normal milk-white 



O 7 



opacity ; the cells are small and arranged in rows irregular 

 in direction. At its deepest part the cells are mostly in 

 rows parallel to the surface. Below this cartilage is a 

 translucent layer 1 mm. thick ; the cells in it are rounded, 

 larger than in the former, and arranged in vertical rows. 

 Beneath this is a layer of similar tbickness in which calci- 

 fication of the matrix is taking place. There is much black 

 pigment in the medulla, mostly following the course of the 

 larger blood-vessels. Preserved in 50 % glycerine. 



Presented by G. /&</, Esq. 



