REPORT ON THE CRUSTACEA MACRURA. 355 



convexly inwards and backwards to the median line, whence a long and slender spine of 

 like appearance and similarly armed projects upwards and backwards. The long spinous 

 processes, judging from Suhm's drawing, appear to be flexible, and were probably bent 

 or arranged in the positions in which they are represented for the convenience of being 

 placed on the paper. 



The pleon is shorter than the carapace and not segmented. It terminates by 

 bifurcating into two narrow, widely separated lobes, each armed with four long, denticu- 

 lated, terminal spines or processes, and a short smooth one on the inner side at the base 

 pointing obliquely inwards and backwards. 



The ocellus is visible between the antennae, and Suhm says that the ophthalmopoda 

 (oc) are visible in an incipient condition to the right and left of the nauplian eye (ocellus). 



The first pair of antennae (ft 1 ) is four-jointed, the terminal joint supporting two long 

 and one shorter ciliated hairs. 



The second pair of antennae (a 2 ) is biramose, the anterior branch, respresenting the 

 flagellum in the adult, is two-jointed, and supports a scapliocerite, which in this stage is 

 multiarticulate and fringed with ciliated hairs on one side and at the extremity, the 

 outer side being smooth and free from hairs. 



The mandibles are visible, and figured in the annexed cut, as well as the first and 

 second pairs of maxilla, at pmx 1 and ma?, as also the maxilliped mxp, and the first pair 

 of gnathopoda gn\ The second gnathopod is absent, and all are fringed with long 

 ciliated hairs ; posterior to these no appendage is present. 



The specimen from wdiich this drawing was taken appears not to have been preserved, 

 and I only know it from Suhm's drawing. It was but little more than half a millimetre 

 in length, and Suhm is most probably correct in believing that it had only recently been 

 hatched, the presence of the yolk-mass clearly demonstrating its immature condition, 

 but the long and plumose cilia are evidence that at least one moult had elapsed after it 

 quitted the ovum. In this stage the ophthalmopoda are not developed, and no 

 appendages are present posterior to the first pair of gnathopoda, and there is no 

 evidence, except the embryonic condition of the ophthalmopoda, that shows any 

 distinction between this Elaphocaris and the Zoea of a Brachyurous Crustacean. 



The next stage of which we have any knowledge was taken on the 13th of March, 

 L875, at or near Station 221, in lat. 0° 40' N., long. 148° 41' E., north of the Admiralty 

 Islands in the Pacific. It is labelled "Sergestes zoea, Elaphocaris" by Willemoes Suhm, 

 and is given on PL LXI. fig. 1. It is about l - 5 mm. in length, from the extremity 

 of the rostrum to the middle of the caudal cleft, and evidently belongs to a species 

 different from Suhm's previous specimen, since it has a long spinous rostrum. The 

 ophthalmopoda are well developed, but no appendages posterior to the gnathopoda are 

 present, and even these are in an immature condition. 



The carapace is dorsally nearly circular, somewhat pointed posteriorly, and armed 



