138 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



Family VI. EXOCORALLANID^. 



Clypeus wide and very short, subtriangular, seen from below con- 

 cealed by the mandibles. Labrum wide and very short, subhorizontal 

 or vertical, seen from below very often concealed by the mandibles. 

 Apical tooth of mandibles of great length; movable lacinia and molar 

 part wanting. 



The first maxilla? are robust; the lacinia of the first article is inflated 

 at the apex and unarmed; third article very robust, from the middle 

 to the apex becoming very much narrower and curved somewhat out- 

 ward, the apex furnished with a single very long and very robust spine 

 curved somewhat inward. Second maxillae short, narrow, feeble, the 

 apex with two free almost rudimentary laciniae. Maxillipeds narrow, 

 free; palp with the antepenultimate article elongated, more than twice 

 as long as wide. 



26. Genus EXOCORALLANA Stebbing.& 



ANALYTICAL KEY TO THE SPECIES OF THE GEXUS EXOCORALLANA. c 



a. Eyes moderate or large, some distance apart in the middle at the upper end. 

 b. Left mandible, seen in position, with the apical part profoundly trifid. Clypeus 



and labrum very conspicuous. 



c. Basal article of the first pair of antennae narrow, without spine. Head of 

 male ornamented with two or more horn-like tubercles. First segment of 

 body not ornamented with tubercles. 



d. Head of male ornamented with three tubercles, two on the dorsal surface 

 and one being the produced median point. Thorax not tuberculated. 



Exocorcdlana tricornig (Hansen) 



d'. Head of male ornamented with two dorsal tubercles. Median point not 

 produced in tubercles. Thorax tuberculated. 



Exocorallana mexicana, new species. 



cf. Basal article of the first pair of antennas dilated, ornamented with spine at 

 inner exposed angle. Head of male ornamented with four horn-like tuber- 

 cles. First segment of body ornamented with two tubercles. 



Exocorallana sexticornis (Richardson) 



b' '. Left mandible, seen in position, with the apical part obscurely trifid or forming 

 a single apex. Labium and clypeus partly or very often entirely covered by 

 the mandibles. 



c. Basal article of the peduncle of the antennulte moderately narrow, seen from 

 below not prominent above the basal joints of the antennae. Last segment 

 of the abdomen not ornamented with basal tubercles near the median line. 

 d. Head of male ornamented with four tubercles. 



Exocorallana quadricornis (Hansen) 

 d'. Head of male not ornamented with tubercles. 



Exocorallana truncata ( Richardson ) 



"See Hansen for characters of family, Vidensk. Selsk. Skr. (6), V, 1890, pp. 311- 

 313, 317, 376. 



& Fauna and Geography of the Maldive and Laccadive Archipelagoes, II, Pt. 3, 

 1904, p. 704. 



<*This key, with the exception of three species which are inserted, is taken entirely 

 from Hansen, Vidensk. Selsk. Skr., 6th ser., natur. og. math., Afd. V, 1890, pp. 

 378, 379. 



