18 



ANATOMY OF AMPH10XUS. 



the buccal cartilages. As pointed out by Johannes Miiller, 

 they are not to be compared with the jaw-apparatus, nor 



to the hyoid or tongue- 

 bone of the jaw-bearing 

 Vertebrates, but they 

 belong to the same cate- 

 gory as the mouth-carti- 

 lages of the Cyclostome 

 fishes (which possess a 

 hyoid cartilage in addi- 

 d.s end tion) and the labial car- 



Fig. 3. Anterior portion of body of young tllagCS of Selachians 

 transparent individual. (After J. MtJLLER, / i i \ 

 slightly altered.) 1Kb > 



ch. Notochord. ci. Buccal cirri, e. Eye- The absence of paired 

 spot. end. Endostyle. f.r. Fin-rays lying in 



the fin-chambers. g.s. Gill-slits ; the skeletal CyCS and of any kind of 

 rods of the gill-bars are indicated by black lines. audit hag b 



nt. Spinal cord, with pigment granules near its J 



base. r.a. Downgrowth from right aorta lying mentioned above. There 

 to the right of vel. the velum ; with velar ten- . 



tacles projecting back into pharynx, w.o. Rad- 1S > however, a median 

 erorgan; ciliated epithelial tracts on inner wh j ch consists of a 



surface of oral hood. J 



comparatively large un- 

 paired pigment spot lying at the anterior extremity of the 

 dorsal nerve-tube.* A row of 

 similar, but much smaller, 

 masses of pigment lie along 

 the floor of the spinal canal, 

 commencing some distance 

 behind the eye (Fig. 3). 



Immediately above and be- Fig. 4. Buccal cartilages of Am- 

 hind the eye-spot is a small P hio * US ' ( ^ fter i MUL , LER ') The 



basal pieces he end to end in the mar- 

 pit in the body-wall reaching gin of oral hood, and each basal piece 



sends up an axial process into the 

 from the OUter Surface of the corresponding buccal cirrus. 



* The eye-spot has been observed to be sometimes broken up into two 

 pigment masses. (See AYERS, No. 105 bibliog.) 



