H CARBONIFEROUS ENTOMOSTRACA. 



would have been required, indicating apparent approximations to existing forms ; and no 

 advantage in the saving of names would have accrued. 



Making the most, then, of the carapace-characters among the fossil Cypridina-like 

 species, and referring them on that basis to their apparent congeners among the published 

 existing forms, we find several which appear to be related to Cypridina (both oval and 

 pyriform), and a few to Brady cinetus and Fhilomedes. Bhomhina is a related Cypridinad. 

 Five kinds of Cypridinal carapace among the Carboniferous specimens have additional 

 features, constituting distinctive characters not known among recent Cypridinads; and 

 thus give grounds for Cypridinella, Cypridellina, Cypridella, Cyprella, and Sulcuna. Two 

 well-marked mutual allies, EntomoconcJms and Offa, are neighbours of the Cypridinadce ; 

 and the recent Polycope is represented. Others of more obsciu'e relationship occur, such 

 as Entomis, with its deep dorsal sulcus. 



We need not hesitate in carefully referring these recent and fossil Entomostraca to 

 the same zoological groups, inasmuch as Cythere and Bairdia are represented by even 

 Silurian carapace-valves ; and we may add that Cypridinada (not yet described) occur 

 in the Upper Silurian strata of the Pentland Hills in Scotland, and in the old pebbles 

 of Silurian or Devonian quartzite in the Conglomerate of Budleigh-Salterton in Devon- 

 shire. 



Taking, then, the simply notched, oval, oblong, and pyriform specimens as Cypri- 

 dina, we find a peculiarly notched and oval species representing Bradycinetus, and 

 some oblong impressed specimens equal to Fhilomedes. A modification of the pyriform 

 CypridincB by the projection of the antero-ventral region marks Cypridinella ; intervention 

 of a subcentral tubercle gives us Cypridellina ; and the superadded nuchal furrow, with 

 augmented tuberculation, characterizes Cypridella. The tubercle is foreshadowed in an 

 occasional specimen of Cypridina, and we see the nuchal impression faintly in the 

 Philomedes ; but, with the high probability that the limbs differed, we take these slight 

 links in their broadest developmental sense, and not as indicating direct alliance. 



The addition of an external annulated ornament brings us from Cypridella to 

 Cyprella; and Sulcuna differs from Cypridella in its peculiar sulcus. 



Returning to Cypridina we trace modifications of the antero-inferior region, beneath 

 the " notch," either by a lessening (as in our C. brevimentum), such as obtains in most of 

 the recent forms, or by increased projection, faintly exhibited in the living C. Zelandica, 

 Baird, and C. luieola, Dana, but in many of the fossils so extremely produced that the 

 antero-ventral quarter stands out like the prow of such an armoured ship as the modern 

 "Ram," typified by the American "Merrimac" and "Monitor." This modification 

 characterizes our Cypridinella. 



In another direction the Cypridinal carapace, becoming very gibbous and subquadrate 

 or globose, has a faint " notch," but a long vertical " gape," and is recognized as 

 Entomoconchus ; further, in this kind of subglobose carapace, with the " sinus" present, 

 but the " gape " reduced to a minimum, we have Offa. 



