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THE AMERICAN NATURALIST [Vol. XLI 



3. In addition to the axillan' glands Schilheodcs giirinus and 

 S. nocturnus possess glands developed about tlu^ pectoial and 

 dorsal spines. These are of the same tyj)e and structure as the 

 axillary glands. The end of such a glaud-l)earing si)ine projects 

 slightly through a slit in the epidermis. 



4. Spine glands are not found in those species which possess 

 well develo])ed serrae upon the spines. 



5. Schi/lxodrs Icpfacanfhus, because of its close relation to S. 



the axillary glands. 



G. A study of the mature glands tends to justify the following 



a. The glands are of epidermal origin; those in the axilla 

 invaginate from the pore, and those in the spines from 

 the slits near the tips of the spines. 



b. The gland sheath is modified corium. 



c. The clavate cells of the skin become the secreting cells 

 of the gland. 



d. The ordinary epidermal cells become elongated, forming 

 the supporting network of the secreting cells. 



e. The glands of the mad toms are essentially like those 



of tlu> weever fishes. 



