470 PYGOCEPHALUS COOPERI 



DESCRIPTION OF PLATE XIII. [XXIX.]. 



Fig. I a. Pygocephalus Cocperi, No. i : nat. size. The Manchester specimen. 



Fig. I b. The same : magnified l| diameter. 



Fig. I t. Thoracic appendage of the same : magnified. 



Fig. 2. Mr. Cooper's specimen, No. 3 : magnified. 



Fig. 3. Mr. Cooper's specimen, No. 2 : magnified. 



Fig. 4. Thoracic appendage of Mysis : magnified. 



Fig. 5. Antennule and antenna of Mysis : magnified. 



Fig. 6. Gonodactylus bent upon itself, in oiithne ; the appendages being omitted : magnified. 



a. Quadrate disk. 



b. Central part of the body. 



c. Semicircular disk. 



d. Marginal portions of carapace. 



c. Tergal surface of abdominal somites. 



En. Endopodite. Ex. Exopodite. 



i'. Antennules. 



2'. Base and inner division of antenna. 



2". Outer division of antenna, or scale. 



