THE TrigZidae have attracted the attention of European anatomists for more than three-quarters of a century on account of the remarkable finger-like processes of the pectoral fins. These processes, which have proved to be free fin rays, were found to be very richly supplied with nerves, and enlargements, or lobes, were found on the dorsal surface of the spinal cord, where these nerves united with it.
Special efforts have been made to discover sense buds or other end organs in the epidermis of these free fin rays.
The strong resemblance to such dermal appendages as barbels, led Merkel ( I ) to characterize them as wholly analogous in structure and function.
No one has hitherto succeeded in finding sense-organs on these rays similar to those found on barbels, and there are great differences of opinion in regard to the peripheral termination of the nerves in these organs.
In the hope of settling some of these questions, I undertook the study of the Gurnards found along the Atlantic coast.
I wish to acknowledge my great indebtedness to Dr. C. 0.
Whitman, Director of the Marine Biological Laboratory at Woods Holl, at whose suggestion the work was undertaken, and also to Dr. J. P. McMurrich for many valuable suggestions received during the progress of the work.
The representatives of the Gurnards found along our coast are different from those found in European waters.
Two species which are quite abundant at Woods Holl were studied ; namely, Prionolus paZm$es Storey, and PviOnotzls evo-Z m s GiZZ (14). These fish may attain the length of fifteen to eighteen inches and weigh one and a half to two pounds, but are generally much smaller.