DECAPODA 



387 



Fig. 618 Palcemonetes vulgaris (Verrill). 



P. vulgaris (Say). Common prawn (Fig. 618). Rostrum long, 

 straight and serrate; length 45 mm.; body translucent, with brownish 

 spots: Massachusetts to Florida; common on rock weed, and eel grass 

 on muddy bottoms, often where the water is brackish or fresh. 



P. paludosa (Gibbes). 

 Length 35 mm.; rostrum serrate 

 below as well as above: in 

 fresh-water lakes and streams 

 in eastern North America (Lake 

 Erie, etc.). 



2. PAUEMON 

 Fabricius. Like 

 Palaemonetes but 



with a 3- jointed mandibulary palp (Fig. 619) : about 70 species, 3 

 American; in salt and fresh water. 



P. ohionis S. I. Smith. Length 6 cm.; carapace about a quarter the 

 length of the body, with a lateral spine on each side: Ohio and Missis- 

 sippi Rivers; often used for food. 



3. PANDALUS Leach. Deep-water prawns. First 

 and second pairs of periopods slender, the first 

 not chelate, the second chelate: 10 American 

 species. 



P. montagui Leach. Length 10 cm.; body with 

 transverse red stripes; appendages thickly spotted 

 with red: Chesapeake Bay to Greenland; Europe; in 

 10 to 100 fathoms. 



4. HIPPOLYTE Leach. First 2 pairs of periopods chelate, the first 

 pair shorter and thicker than the second; abdomen sharply bent down 

 at third segment; mandibular palp present: numerous species, about 

 30 American. 



H. pusiola Krb'yer. Length 25 mm. ; 

 pale gray or flesh color, brightly spotted 

 with red, usually with a mid-dorsal 

 white stripe, and sometimes 

 Avith transverse bands of red 

 and white: often common on 

 rocky bottoms in shallow water from Vineyard Sound to Greenland; 

 Europe. 



5. VIRBIUS Stimpson. Similar to Hippolyte but without a man- 

 dibular palp: many species, 2 American. 



V. zostericola S. I. Smith (Fig. 620). Rostrum straight and as 

 long as the carapace, the latter being smooth and with 3 spines on an- 



Fig. 619 Mandible 



of Palcemon, 



showing palp 



(Smith). 



Fig, 620 Virbius zostericola 

 (Smith). 



