Length 30-67 mm (Eusirus perdentatus 1). Head subequal to pereonites I-II combined, lateral lobes broadly rounded. Pereonites V-VII, pleonites I-III with dorsal spines, urosomite I carinate. ART I of peduncle of ANT I with strong distal teeth on inner margin, small distal denticle on ventral margin. Ventral margin of ART 4 of peduncle of ANT II serrate. Eyes large, pear-like, in males occupying main part of lateral surface of head (often even fused dorsally), in females not so large. ART 4 of P III-IV longer than 5 or 6. ART 5 of P V-VII only slightly longer than ART 4.