42 TRUE CRABS OF MONTEREY BAY 



Cancer magister Dana. 



Plate IX, fig. 25. 



Cancer magister Dana, Proc. Acad. Nat. Sci. Phila., viii, 78, 1852. — Holmes, Occas. 

 Papers Calif. Acad. Sci., vii, 50, 1900, and synonymy. — Rathbun, H. A. E., x, 

 177, 1904. 



This species is common in the Monterey markets, but has not been 

 obtained in any of the dredging done by the laboratory. 



Cancer gracilis Dana. 

 Plate IX, figs. 26-28. 



Cancer gracilis Dana, Proc. Acad. Nat. Sci. Phila., vi, 73, 1852. — Holmes, Occas. 

 Papers Calif. Acad. Sci., vii, 52, 1900, and synonymy. — Rathbun, H. A. E., x, 

 177, 1904. 



Cancer gracilis is represented by a considerable number of speci- 

 mens, both young and adult, all obtained by dredging, though in Puget 

 Sound it is an abundant shore crab. On several occasions the young of 

 this species has been found in considerable numbers clinging to the sub- 

 umbrella of various medusae. These have all been of small size — 5 to 10 

 mm. — but it was not until the summer of 1908 that younger stages were 

 found. On one occasion a number of medusae were collected and in exam- 

 ining these many very young crabs were obtained and a smaller number 

 of megalops. Some of these were kept alive until the molt to the young 

 crab stage took place, so that there can be little doubt that the specimens 

 were really the megalops of gracilis. Later megalops were obtained from 

 other species of medusae, and crabs of a slightly larger size than those 

 found on the jelly-fish were dredged in considerable numbers ; it would 

 appear, therefore, that in the case of gracilis, at least a considerable num- 

 ber of individuals pass that portion of their life history from the end of 

 the free-swimming stage, probably early megalops, until reaching a size 

 of 15 to 20 mm. clinging to medusae, after which they drop to the bottom 

 and live in the manner of the adult. I have found no other species than 

 gracilis on medusae though Miss Rathbun reports one specimen of jordani 

 from the same situation. It would be interesting to know if this form of 

 life history were universal with gracilis and if it were common in any 

 other species. 



Color in life olive overlaid with minute reddish brown spots, which 

 are more numerous on the teeth of the antero-lateral margin and on the 



