PLANKTON OF THE WOODS HOLE REGION 159 
The following Macrura were taken in the surface collections for 1922-23: 
Crago septemspinosus (Say). Homarus americanus, Milne-Edwards. 
Palzmonetes vulgaris (Say). Emerita talpoida (Say). 
Hippolyte zostericola (Smith). Upogebia affinis (Say). 
Naushonia crangonoides, Kinglsey. Pagurus sp. 
Callianassa stimpsoni, Smith. 
BRACHYURA 
Larval crabs are always present in the summer plankton in large numbers and 
form very important food for many fish. As few of the zoée had been worked out, 
they were a source of much trouble until the many forms were finally identified. 
The development of the various species will be taken up in a later paper. 
All the crabs of this region have free-swimming larval stages, although certain 
species are seldom taken in surface collections. The megalops are found in smaller 
numbers than the zoée. Investigation showed that in this stage the young crab 
is usually found among the eelgrass and een nara parece rs 
. a = a n lo} 
Fucus. Itcanswimaswellasthezoéa 4... seroratus 
but remains closer to the bottom. camer borealis 
After hard winds large numbers were  ™221pes ccellatus 
Tallinectes sapidus 
3 2 4 2 2: Carcinides métnas 
a < C -) = Libinia spe 
Polyonyz macrocheles (Gibbes) Heteroorypta gramilata 
Pinngtheres ostreun (Say) ari Pelia mtica 
Pinnixa scayana Stinpson ft Heopanope texana sayi 
sone som ee Poiyeays masochle 
Ovalipes ocellatus (Herbst) = Pimiza chébtopterana 
Carcinides maénas (Linnaeus) SESS SHH! Pinniza sayana 
Planes minutus (Linnaeus) Seeeeteees Pimnotheres maculatus 
Uca pugnax (Smith) a5 Oca spo 
Dea pugilator (Bosc) SS @yas coarctatus Leach 
Fic. 58.—Brachyura occurring rarely in surface Fig. 59.—Occurrence of larval forms of Brachyura in surface 
collections of 1922. Eggs of Planes minutes collections of 1923. No observations were made from 
(Linnaeus) from an adult taken in the tow August 22 to September 18. Megalops of Hyas coarctatus 
were hatched in the laboratory Leach were obtained from Muskeget Channel on August 25 
often taken in the nets. The megalops transforms into the “young crab” stage in a 
single molt. The ‘‘young crabs” are very rarely found swimming, except in the 
species Pinniza chextopterana and P. sayana. These have no megalops stage but 
change directly from the zoéa into a young crab, which may be compared with 
the megalops of other species, for they swim about in much the same manner and are 
often very abundant in the plankton. 
The zoéz of Uca were rarely taken at the surface. Megalops appeared on only 
two occasions, after storms. This seems very strange, because Uca is probably the 
most abundant crab found in this region. Hymen reports the zoé as being very 
abundant in the surface collections at Beaufort, N. C., at all times during the 
summer. I believe that the fiddler crabs of this region have a very short larval 
period in which the zoée as well as the megalops remain at or near the bottom. 
Carcimides mznas larve may have similar habits, in this locality at least, for zoéz 
were taken on only three days in October, 1922, and on one occasion in 1923 (figs. 
58 and 59). 
