2 BULLETIN 166, UNITED STATES NATIONAL MUSEUM 



On the Atlantic coast the Carnegie Marine Biological Laboratory 

 at Tortugas, Dr. William H. Longley, director, has enlarged its scope, 

 enabling Dr. Schmitt and others to make expeditions to deeper water 

 than previously. The results have added notably to our knowledge 

 of the fauna of the region. The Johnson-Smithsonian expedition of 

 1933 to the Puerto Rican Deep, Dr. Paul Bartsch, naturalist, secured 

 a goodly number of Gymnopleura and Oxystomata, including an un- 



FiGURE 1.— Diagram of dorsal view of an oxystomatous crab, showing the terms used in description. By 



Waldo L. Schmitt. 



described species. Dr. Horace G. Richards has continued his con- 

 tributions to our collections, while Stewart Springer discovered a 

 new giant Cala'p'pa in the Gulf of Mexico. The State University of 

 Iowa has been very helpful in putting its collection of Decapoda at 

 our disposal; it is now part of a loan deposit in the United States 

 National Museum. 



MEASUREMENTS AND ABBREVIATIONS USED 

 EXPLANATION OF MEASUREMENTS 



The length of the carapace, unless otherwise stated, is measured on 

 the median line, from the anterior to the posterior margin. 



The mdth of the carapace is measured at the widest part. 



The fronto-orbital width or exorbital width is measured from the 

 outer angle of one orbit to the outer angle of the other. 



The length of the articles of the chelipeds and legs is measm-ed on 

 the upper or anterior margin. The length of the whole cheliped or 



