in the Museum of the Smithsonian Institution. 135 



toothed above, the posterior tooth aboA'e being placed a little before 

 the middle of the carapax. Terminal half of the rostrum styliform, 

 without teeth above. Lateral furrows of the rostrum distinct, ex- 

 tending to the posterior tooth. Antero-lateral spine and sulci nearly 

 as in P. setiferus. Antennulse with the inner flagella much longer 

 than the outer ones, and about as long as the carapax. Spines on the 

 bases of the first and second pairs of feet very small. In the female 

 the feet of the last three pairs bear lamelliform processes on the inner 

 sides of the coxse, and the sternum between the bases of the posterior 

 feet bears a short but much projecting dentiform median carina. The 

 abdomen is similar to that of P. setiferus. 



Length of the largest specimen in the collection, six inches, exclud- 

 ing antennaj. Length of flagellum of antennae, about twelve inches. 



It differs from P. setnisulcatus in its longer rostrum and an- 

 tennulse, and from P. carinatus in the oblique position of the 

 anterior cervical sulcus. 



Found at Panama by J, H. Sternbergh, Esq. 



Penaeiis con§tricfus, nov. sp. 



The abdomen is naked and glossy, but the carapax, particularly 

 toward the front part, is pubescent with extremely minute setae, di- 

 rected forward, so that the surface is easily rubbed in a forward di- 

 rection, but resists strongly when rubbed backward. The hepatic 

 spine, and antennal spine, ridge, and sulcus are well marked or even 

 prominent. The cervical sulcus is well-marked, and may even be 

 traced in the middle of the back on either side of the median carina ; 

 it is deflected near its anterior extremity, running to the inferior 

 margin of the carapax, and forming a deep groove parallel with the 

 anterior margin ; giving the carapax, seen from below, the appearance 

 of being constricted close to its anterior extremity. A furrow along 

 the inferior side of the antennal ridge flows into the cervical sulcus 

 at the point where the latter is deflected. The angle at the outer 

 base of the eye-peduncle jirojects a little, but scarcely forms a spine. 

 The carapax is carinated on the anterior three-fourths of its length, 



