132 BULLETIN OF THE BUREAU OF FISHERIES. 



EXPLANATION OF PLATES. 



KEY TO LETTERING. 



b, bothrium. m, muscle tissue. 



bl, blastocyst (plerocercus). o, accessory bothria] organ. 



(. cyst. p, proboscis. 



ca, calcareous body. sc, scolex or larva. 



cb, contractile bulb of proboscis. sh, proboscis sheath. 



el. connective tissue. st, beginning of strobile. 



PLATE I. 



Fig. 1. Specimen of butterfish (Poronotus triacanthm) laid open to show cysts of Otnbothrium crtnacolh. 



The principal regions of infection are shown somewhat diagramaticallv. The number of cysts shown 



in the sketch is far less than may be seen in a badly parasitized fish. Sketch made from a fish 22 



centimeters in length, from Barnegat, N. J. 

 Fig. 2. From life. Cluster of cysts from the butterfish. The cluster measured 2.1 by 1.2 millimeters in the 



two principal diameters. The scoleces were active, their average length about 1 millimeter. 

 Fig. •'-!. A blastocyst from cluster shown in figure 2, compressed so as to show the distinctive features of the 



species; length of larva 0.8 millimeter. 

 Fig. 4. Another cyst from same host. The blastocyst, which does not completely fill the cyst, measured 1.24 



by 0.8 millimeter in the two diameters. 

 Fig. 5. Blastocyst of figure 4 removed from the cyst. The head and part of the neck of the scolex is emerging 



from the blastocyst and the proboscides are everted. 

 Fig. 6. Cyst with three blastocysts containing scoleces, from serous coat of intestine of squeteague (Oynosdon 



regalis). The walls of the cyst were transparent : blastocysts and scoleces active. Cyst 1.8 by 1.12 



millimeters in the two diameters. 



PLATE II. 



Fig. 7. Cyst, blastocyst, and scolex from butterfish, life. Diameter of cyst, I)..") millimeter. 



Fig. 8. Blastocyst with scolex emerging — removed from cyst shown in figure 7. 



Fig. 9. Scolex (larva) removed from blastocyst. 



Fig. 10. Part of bothrium highly magnified, showing the accessory organs retracted. 



Fig. 11. One of the accessory organs, everted, still more highly magnified. 



Fig. 12-16. Different views of proboscides highly magnified. Figures 12 and 13 are views of portions of the 

 proboscis near the base. The sketches were made with the aid of a camera lucida, 1-inch eyepiece 

 and one-twelfth objective, and represent an enlargement of about 720 diameters. 



Fig. 17. Cyst, blastocyst, with scolex and muscle tissue of host, compressed; sketched from specimen mounted 

 in balsam. X about 60. 



Fig. 18. Section of muscle tissue witli fifteen cysts, X about 6. The muscle fibers are cut transversely in the 

 upper and longitudinally in the lower part of the figure. 



Fig. 19. Section of muscle tissue with ten cysts, X about 60. a, empty cysts; blastocysts with larva? appear in 

 other sectionsof the series; d, neck of scolex cut transversely , showing the four proboscides: < , scolex cut 

 nearlv longitudinally; f, bothria cut nearly transversely; </, section passes through the bothria and two 

 of the contractile bulbs nearly longitudinally; the neck of the larva has been bent and is largely missing 

 from this section; It, diagonal section of neck of larva — at one end of section the proboscides are cut 

 transversely, at the other two of them appear but cut longitudinally: i, section shows blastocyst but 

 misses the larva, which may be seen in another section of the series. 



