INVERTEBRATE 



\ ZOOLOGY 



^ A HMttM Crustacea 



A V f 1 > I 1 



Xo. 8. — Reports on the Dredging Operations off the West Coast of 

 Central America to the Galapagos, to the West Coast of Mexico, 

 and in the Gulf of California, in charge of Alexander Agassiz, 

 carried on by the IT. S. Fish Commission Steamer "Albatross," 

 during 1891, LlEUT. COMMANDER Z. L. TANNER, U. S. K, 

 Commanding. 



[Published by Permission of Marshall McDonald, U. S. Fish Commissioner] 



XIV. 



The Pelagic Schizopoda. By Arnold Ortmann. 



EUPHAUSIACEA. 



Thysanopoda agassizi, nov. spec. 



Form of body rather stout. Antero-lateral angles of the carapace rectan- 

 gular, rounded, and without a denticle. The lateral margins without denticles. 

 Rostral projection triangular, sharply pointed, longer than the eyes. Anterior 

 part of the carapace slightly keeled above. Third, fourth, and fifth segments 

 of the abdomen projecting posteriorly as acute dorsal spines. Sixth segment 

 somewhat longer than the preceding. Preanal spine small, simple. Eyes 

 moderate. The first joint of the antennular peduncle furnished at the distal 

 end with a dorsal cushion-like, densely hispid elevation. This elevation pro- 

 jects forward as an acute, somewhat outwardly directed, spine-like lappet, nearly 

 as long as the second joint. The outer anterior corner of the first joint bears a 

 smaller spine. The second joint projects forward as a spine-like lappet similar 

 to the first joint. The outer corner of the antennal scale bears a denticle. 

 Telson with 10 to 12 pairs of dorsal denticles, inner plate of the uropoda 

 shorter than the outer, the latter as long as the telson. Length, 19 mm. 



This species is related by the long spine-like lappets of the antennulae to 

 Th. monacantha Ortmann, and by the hispid cushion of the first joint of the 

 antennulae to Th. obtusifrons Sars. But it may be recognized by the acute 

 rostrum, the absence of lateral denticles on the carapace, and the presence of 

 three dorsal abdominal spines. 



VOL. XXV. — NO. 8. 



