6 ATHERINID^: SILVERSIDES 



Archomenidia, new genus (sallei). 

 CiiiROSTOMA REGANi, new spccics. 

 Chirostoma consocium, new species. 



The Atherinid^ find their place in the suborder Percesoces, a 

 group which, from time to time, has been variously enlarged to include 

 a number of unrelated families. . It should apparently be restricted, at 

 least insofar as the living forms are involved, to include only the Sphy- 

 R^NiD.E (Barracudas), Mugilid^ (Mullets), and the Atherinid^. 

 The peculiar fishes comprising the family Polynemid^ (Rhegnopteri, 

 or Polynemoidea) are superficially much like the Mugilid.e, and 

 structurally resemble the Percesoces, especially the Sphyr.enid^, 

 quite closely.^ The two groups should perhaps be united to form the 

 primary s'ubdivisions (Mugiloidea, Polynemoidea) of the Percesoces. 

 The relationships of the Atherinid.e to the Mugilid^ and Sphyr^nid.e 

 are indicated by the following analytical key: 



Key to the Families of the Percesoces 



o'. Lateral line present, continuous ; pectoral fin placed rather low ; mouth usually 

 larger, with stronger teeth, especially on the palate : teeth implanted in deep 

 sockets; maxillary with a supplementary bone forming a knob-like projection 

 posteriorly ; "third and fourth superior pharyngeals separate ; supraclavicle 

 not reduced in size ; lower limb of post-temporal not attached to opisthotic 

 by suture; e.xoccipitals meeting above basioccipital ; alisphenoids meeting; 

 ethmoid a thin plate, entirely superior, extending to and forming edge of 

 rostrum ; anterior neural spines normal ; parapophyses not developed on 



anterior vertebrae," ^ directed downward ; vertebrae 24 Sphyr^nid^ 



a*. Lateral line absent, or very incompletely and irregularly developed ; pectoral 

 fin placed high (Nannatherina excepted) ; mouth generally smaller, usually 

 with fine teeth, which are never imbedded in deep sockets ['-^ palatine teeth' 

 fine (Atherinosoma excepted), or absent; no supplementary bone on maxil- 

 lary ; "third and fourth superior pharyngeals of each side anchylosed ; supra- 

 clavicle reduced in size ; lower limb of post-temporal attached to opisthotic 

 by ligament or suture ; exoccipitals not meeting above basioccipital ; ali- 

 sphenoids not meeting; ethmoid normal, not overlying prefrontals and vomer 

 or extending to lateral edge of rostrum; anterior neural spines laterally flat- 

 tened; parapophyses developed on all abdominal vertebrae" (Starks, /. c), 

 directed outward, 

 fc'. Vertebrae 24 to 26 ; anal fin with two or three spines ; head more obtuse ; 

 "lower limb of post-temporal attached to cranium by dentate suture ; basi- 

 sphenoid absent ; myodome not opening to exterior posteriorly ; foramen 

 magnum region produced ; superior pharyngeals of complex shape, not 

 bearing teeth" (Starks, /. c.) Mugilid.^. 



1 Regan, Proc. Internal. Zool. Congr., 7, 847, 1907 (1912; adv. prints 1910). 



2 Starks, Proc. U. S. Nat. Mus., 22, 1-10, pis. 1-3, 1910 (October 7. 1899). 



3 In some species of Chirostoma, as C. sphyr^na, the gape is wide, and the 

 teeth strong and set in shallow sockets, thus approaching those of Sphyr.?;na. 



