42 ALLEN 



in many important details from the forms that have already- 

 been studied, namely : Squalus, Raja, Torpedo, Amia 

 ( = Amiatus), Cyprinus, Leuciscus, Salmo, Lucius (= Esox), 

 Pe?'ca, Lophius, Pleuronectes and Uranoscopus . The lym- 

 phatics of the Loricati therefore appealed to me as a subject 

 worthy of study ; hence this paper, which deals with the distri- 

 bution of the lymphatic vessels in the head, dorsal, and paired 

 fins of Scorpainichthys. 



Two investigators of this subject in selachians, namely, 

 Robin (23) and Mayer (18) deny the existence of lymphatics in 

 fishes other than the visceral system. They consider the super- 

 ficial and profundus vessels of the head and trunk as veins, 

 and their sinuses they regard as venous sinuses. If this is 

 true for selachians, it is certainly not true for the teleosts. 

 In Scorpceuichthys wherever there are blood-vessels and con- 

 nective tissue there are lymphatics. Strange to say, the 

 lymph and the plasma of the blood of this group has a green- 

 ish tinge, so that in an uninjected specimen the lymphatics, 

 although lighter in color, might readily be taken for veins. 

 Lymph usually contains some red corpuscles, often sufficient to 

 give it a red tinge. Whether they have come directly into the 

 lymphatics through the spleen and lymphatic glands, or through 

 venous-lymphatic openings, or have transuded through the 

 walls of the blood-vessels into lymphatic spaces and thence into 

 the lymphatic vessels is still an open question. If, however, 

 some lymph be drawn out with a pipette from the myelonal or 

 superior longitudinal spinal lymphatic trunk, lying in the spinal 

 canal above the cord, or from any of the lymphatic sinuses, and 

 ejected into a bottle, and some blood be placed in a second 

 bottle, the difference can quickly be detected upon the addition 

 of a little alcohol. Most of the corpuscles of the lymph are color- 

 less, while those of the blood have a dark brown color. The 

 entire visceral lymphatic system can often be injected from the 

 myelonal lymphatic trunk, which would hardly be possible were 

 it a vein ; and further, the arrangement of what has been desig- 

 nated as the neural lymphatic vessels, goes to prove that they 

 are a part of a distinct profundis system. In front of each neu- 

 ral spine there is a neural lymphatic vessel, which empties into 



