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Bashford Dean hiemorial Volume 



figure 78), presumably draining the blood from smaller vessels in the gill'septum, was 

 found in the proximal portion of the septum. Just proximal to the main afferent artery 

 of the gill-arch, in the location where an extension of the coelomic cavity presumably 

 occurs in the early embryo, there is a fairly large space which probably represents a 

 lymphatic vessel whose thin wall is incompletely preserved. 



The distribution of arteries within a gill of Chlamydoselachus is essentially the same 

 as in other elasmobranchs, e. g., as in Heptanchus (Text-figure 81, p. 423); in Scyllium 

 (Text-figure 112); and in selachians generally (Text-figures 113 and 114). Of these 

 figures, Corrington's (my No. 114) is the only one showing an intermediate branchial 



<^^^ ^/^ny\ . OR 



^SC^ 



CT >^Qr 



ExbC 



/BCA 



Text-figure 114. 

 Frontal section through a shark-gill, drawn semidiagrammatically. 



ABA, afferent branchial artery; ABAr, afferent branchial arteriole; AdA, adductor arcuus; AECA, anterior efferent' 

 collector artery; AGF, anterior gill-filament; Cb, ceratobranchial; CS>\, constrictor superficiahs; CT, connective tissue; 

 EBAr, efferent branchial arteriole; ExbA, extrabranchial artery; ^yhC, extrabranchial cartilage; GR, gill-ray, distal portion 

 not shown; GR((, gill-raker; GS, gill-septum; lb, intrabranchialis; IBCA, intermediate branchial commissural artery; PECA, 

 posterior efferent collector artery; PGF, posterior gill-filament; Pot, post-trematic ramus, branchial nerve; Prt, pretrematic 

 ramus, branchial nerve; V7v{BV, ventral nutrient branchial vein. 

 After Corrington, 1930, Fig. 10, p. 200. 



commissural artery {J.BCA) connecting the two efferent-collector arteries of a single gill. 

 Such arteries exist in Chiaraydosdachus (Text-figure 110) as well as in many other elasmo- 

 branchs. In some of my sections, I have observed a small artery in the appropriate 

 location for an intermediate commissural artery but was unable to trace its connections 

 due to the lack of a sufficient number of sections in the series. 



The gill-filaments of CHam-jdoseXadms contain few capillaries; they consist chiefly 

 of connective tissue traversed by arterioles and bounded by a very thin integument. 

 They serve, therefore, mainly as supports for the lamellae which are the essential organs of 

 respiration. The lamellae are exceedingly rich in capillaries. In a section, such as that 

 shown in outline in my Text-figure 80 (p. 422), most of the capillaries are cut trans- 

 versely. Since the lamellae are only slightly thicker than the capillaries when the latter 

 are distended with blood (as they usually are in my sections), each capillary comes in 

 contact with the integument on two sides. So rich is the capillary plexus that there 

 is scarcely any space between capillaries; in sections where the capillaries are cut trans- 

 versely they look somewhat like a string of beads. 



