304 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 108 



his report on the Galatheidae obtained by the Atlantis expeditions 

 to the West Indies. 



Genus Galatheascus Boschma 

 Galatheascus ininutus Boschma 



Figure 4,o-(i 



Galatheascus minutus Boschma 1933, pp. 476-478, fig. 1 (external appearance), 

 figs. 2, 3 (transverse sections); 1947, pp. 2-4, fig. 1 (attached to host). 



Type specimen on Galathea nexa Embleton, from Oban, Scotland. 



Material examined: Off Cayo Coco, north coast of Cuba, 180 

 fathoms, 1939; two specunens on one Munida stimpsoni A. Milne 

 Edwards. Atlantis Coll. MCZ 11344. 



Gulf of Mexico, Blake Station 45, lat. 25°33' N., long 84°21' W., 

 101 fathoms, 1877-78; one specimen on Munidopsis barbarae (Boone). 

 Blake Coll. MCZ 11719. (Chace, 1942, p. 81, mentions this specimen. 

 The host is an intersex.) 



Off Cape Lookout, N. C, Fish Hawk Station 7302, U. S. Fish 

 Commission, 7K fathoms, July 24, 1902; one specimen on Munida 

 irrasa A. Milne Edwards. USNM 100944. 



Off Fort Pierce, Fla., Combat Station 235, lat. 27°27' N., long. 

 78°58' W., 180 fathoms, Feb. 2, 1957; one specimen on Munida 

 schroederi Chace. USNM 100947. 



All five specimens are oriented with their long axis perpendicular 

 to the main axis of the host and with the anterior end directed towards 

 the right. The site of attachment is on the second or third abdom- 

 inal segment. The largest parasite, found on Munida schroederi, 

 measures 7 mm. in length, 4 mm. in width, and 3 mm. in thickness; 

 the smallest, found on Munidopsis barbarae, measures 3 by 2 by 1.5 

 mm. All have developing embryos in the mantle cavity and are 

 therefore mature animals. 



The mantle opening in three of the specimens is small, indistinct, 

 and narrow, but in the parasites of Munidopsis barbarae and Munida 

 schroederi it is wider and surrounded by an elevated rim. The short, 

 thin stalk, which is oval in cross section, arises in the median dorsal 

 part of the body. The smooth external cuticle is only about 4 microns 

 thick except where it forms an inconspicuous shield around the base 

 of the stalk. 



In order to study the internal cuticle, one of the specimens occur- 

 ring on M. stimpsoni was macerated in KOH. Retinacula were found 

 on the cuticle covering the visceral mass but not on the lining of 

 the mantle. They consist of one to three spmdles having a length 

 of 7 to 10 microns and a width of 2 to 3 microns. The retinacula of 

 Galatheascus striatus, which they resemble in all respects except size, 

 are 20 to 25 microns long. 



