SEXUAL CHARACTERS — ELASMOBRANCH FISHES 



377 



confined to, the smooth claspers of Raia, Lamna, and Rhina, 

 which possess a gland, however different in function the other 

 cells of the gland may be, and is not discernible in types possess- 

 ing siphons and roughly denticled claspers, such as those of 

 Mustelus, and Scyllium. 



THE LABIAL ORGAN 



On the outer border of the upper lip of Rhina squatina near 

 the commissures on either side is a small patch of tissue which 



m. 



) 



K. 



Fig. 12 Rhina squatina. Diagrams of transverse sections of the clasper 

 gland to show its epidermal origin and subsequent invagination to form a closed 

 tube. 



one would conjecture from its position to be a sensitive area or 

 organ of special sense, e.g., smelhng. I was much surprised, 

 therefore, on sectioning this so-called organ to find that it con- 

 sisted of a mass of goblet-cells, and was precisely of the same 



JOURNAL OF MORPHOLOGY, VOL. 35, NO. 2 



