The Anatomy of Chlamydoselachus 



469 



Arterioles within the Gills. — In searching the literature on Chlamydoselachus, 

 I have found nothing on the blood-vascular system within a gill proper. In order to study 

 this I have been obliged to prepare serial sections of gill-arches and holobranchs excised 

 from my specimens. 



The general plan of the blood- vascular system within a gill is indicated in my Text' 

 figures 78, 79 and 80 (see pages 421 and 422), which do not, however, show any capil- 



n aef 



im 



Pl 



^^ P^f b Irk 



prnc 



Text-figure 112. Text-figure 113. 



Sections through gills of elasmobranchs, showing afferent and efferent vessels. 



Text-figure 112. Section across gill-bar of Scyllium canicula, late embryo 32 mm. 

 long, showing blood supply to lamellae. 



aef, anterior efferent artery; af, afferent artery; al, anterior lamella (filament); b, branchial bar; em, 

 external constrictor muscle; gr, gill-ray; gr% gill-raker; im, adductor branchialis muscle; n, nerve; 

 pef, posterior efferent artery; pl, posterior lamella (filament) continued into external filament (not 



present in adult); s, gill-septum. 



After Goodrich, 1930, Fig. 516. 



Text-figure 113. Diagram illustrating the structure of a gill of a selachian. 



aef, anterior efferent artery of arch; af, afferent artery of lamella (filament); al, anterior lamella (fila- 

 ment); gr, gill-ray; Im, capillary network; pef, posterior efferent artery; pl, posterior lamella (filament); 

 prn, pretrematic nerve; prnd, branchial muscle; ptn, post-trematic nerve; s, outer region of septum; 

 sc, superficial constrictor muscle; s\, skeletal arch. 

 After Goodrich, 1930, Fig. 517d. 



laries. An afferent artery, (af. hr. a. in Text-figure 78), coursing along the outer side of 

 the gill-arch, gives off a branch (afferent branchial arteriole) to each filament. Each 

 afferent arteriole passes along the base of the corresponding filament (Text-figure 78), 

 giving off numerous branches to it (Text-figures 79) and also to the septum. The precise 

 manner of this branching has not been fully worked out, since the task requires an elabo- 

 rate reconstruction, but it is evident that many of the arterioles are here somewhat 

 lacunar in character. An efferent branchial arteriole (ef. hr. a. in Text-figure 78) courses 

 along the outer edge of each filament, returning the blood from the capillaries of the 

 filament to an efi^erent-collector artery of the gill-arch. A fairly large vein, (v. in Text' 



