628 Brady and Norman — Monograph of the Marine and Freshwater Ostraeoda 



The first maxillse are furnished with several lobes and a two-jointed palp, 

 the terminal joint incurved, and terminating in spines or ungues. Second and 

 third maxillae in Asteropidce are in the form of very simple, seta-edged laminse ; 

 in Cypridinidce, Rutidermatidce, and Sarsiellidce^ maxilliform, consisting of one or 

 several lobes, and behind furnished with thin, seta-surrounded vibratory laminse. 

 In Conchceciadce these limbs are still small, but many -jointed, pediform, and 

 ending in ungues, while the vibratory laminae are greatly reduced in size. 



The last limb in the Conchceeiadce is very minute, and consists of two little 

 joints, the last terminating in setae. In all the other families this limb assumes 

 a remarkable and very distinctive character ; it is long, cylindrical, and closely 

 annulated, and thus vermiform, and is carried reflexed upwards and backwards : 

 its extremity is divided into two lip-like lobes, which are pectinately cleft, or 

 otherwise variously formed in the different species : around this extremity of the 

 limb, and also on the sides at a short distance behind it, are numerous long 

 spine-like appendages, which are themselves armed with a few aculeate projec- 

 tions on each side towards their extremities. 



The caudal laminae remind us of those of the Cladoeera : they consist of a 

 pair of plates, commonly elongated, but sometimes not so long as wide, their 

 margins beset with numerous ungues, which gradually increase in length to the 

 end. In most of these families a heart is present. The Asteropidce alone are 

 provided with a series of dorsal branchial plates. The ova are carried in most 

 genera, as in the Cladoeera, within the shell behind the hinder portion of the animal, 

 which is attached to the shell by dorsal and lateral muscles about the middle of 

 its length. 



Of the very remarkable genus Heterodesmus, described by one of us in the 

 " Transactions of the Zoological Society " for 1865, nothing is known except the 

 shell. It seems, however, to be nearly allied to the fossil genus Entomoconchus, 

 M'Coy, and probably will be found to belong to the group Myodocopa. 



Fam. 1. — ASTEROPID-ffi, Brady and Norman. 



Shell more or less oblong or elliptical, smooth, glabrous, deeply incised in 

 front, rostral portion widely rounded, little produced downwards ; posterior ex- 

 tremity in ? well rounded ; in S lips of valves slightly pouting behind. Anten- 

 nules short and stout, penultimate joint in both sexes furnished with an unguis, 

 antepenultimate bearing a conspicuous sensory organ of different structure in 

 the two sexes ; apical setae subequal in ? , in c? two of these setae are excessively 

 long. Mandibular foot very strong ; basal joint with a large, reflexed, falcate 

 masticating process, which is denticulate on the edge. First, second, and third 

 maxillae all thin and membranaceous, and fringed in almost all parts with setae. 



