REPORT ON THE CRUSTACEA MACRURA. 237 



Each somite of the pleon is armed at the postero-lateral angles with a long spine. 

 One somite more than is normal has erroneously been figured. 



None of the pleopoda are represented, even in an incipient condition, excepting the 

 posterior pair, which is short, biramose, and furnished with a few short hairs. 



This specimen was taken in the same locality as the last, and is larger by three- 

 tenths of a millimetre. 



On Pis. XLVI. (fig. 1), XLVII. (figs. 1, 2, 3), and XLVIII. (figs. 1, 2, 3, 4), are 

 several illustrations of what I believe to be the young of one or more species of Penseus, 

 or of some closely allied genus. 



Although I have not had the opportunity of tracing the continuous development in 

 the life history of the animal, I feel assured that these are the young of this or some 

 closely allied genus. This also is the opinion of Claus concerning his younger specimens, 

 and I believe that the three figures given from Dr. v. Wdlemoes-Suhm's drawings are those 

 of the same, and not of Sergestes as labelled by him. Assuming this, we have a probable 

 scries in very close connection, from the earliest forms given by Claus, which correspond 

 with the later series of figures given by Fritz Muller, to that of the adult as shown in 

 some of the younger specimens illustrated in this Report. 



Claus, in his Crustaceen System, has on pi. ii. given figures of the Zoea of Penseus. 

 The first (fig. 1) is a stage earlier than the youngest given by Suhm. The third (fig. 3) 

 corresponds with the third, or E, of Suhm. They differ in having no froutal rostrum, 

 and in not having any spines attached to the lateral margins of the somites of the 

 pleon as in the first and second stages, in having the ophthalmopoda undeveloped, 

 and in having one lateral tooth on each side of the fifth somite of the pleon. 



On PL XLVIII. (fig. 2) of this report, there is given an illustration of an animal that I 

 consider to be the young of Penieus at the same stage of development as in the last 

 of the drawings of Suhm (fig. 45) (E). It is represented as showing the dorsal surface, and 

 therefore exhibits such features as the central spines on the somites of the pleon, and the 

 two frontal spines which are here shown as being on the dorso-frontal surface of the 

 carapace rather than on the margin. 



Length, 3 mm. (0-12 in.). 



Habitat. — Taken on the 3rd of April 1875, in the Pacific, south of Japan, between 

 Stations 229 and 230. 



Rostrum as long as the carapace. Pereion developed posteriorly to the carapace, 

 and equal to it in length. Pleon about as long as the carapace and pereion combined. 

 Carapace armed with two long teeth, one on each side posterior to the first antenna?, and 

 none upon the margin. 



The somites of the pereion are short, smooth, subequal, and unarmed. 



Pleon dorsally armed with a sharp central tooth on the posterior margin of each 



