RAJU: THE GENUS MONOGNATHUS 



The myotomes of the nemichthyid larvae are 

 W-shaped whereas those ofCyema are V-shaped. 

 The intestine is looped in Cyema whereas it is 

 straight in the nemichthyid larvae. On the other 

 hand, the larva of Cyema closely resembles those 

 of the Saccopharyngiformes in the size and shape 

 of the body, myotome shape, looped intestine, 

 position of the vent, and elongate suspensorium. 

 Bertin (1937b) has pointed out some of the larval 

 and osteological resemblances between the 

 Cyemidae and the Saccopharyngiformes and at- 

 tributed the similarities of the beak of the 

 Cyemidae and Nemichthyidae to convergent 

 evolution as the beak in Nemichthys is mainly 

 formed by the elongation of the vomer, but in 

 Cyema by the two maxillaries. 



The four families — Cyemidae, Monognathidae, 

 Saccopharyngidae, and Eurypharyngidae — share 

 some basic characters such as short, deep bodied 

 larvae with V-shaped myotomes, looped gut, 

 elongated suspensorium, and a degenerate eye in 

 the adult condition. The striking similarities of 

 these larvae and their differences with the 

 larva of Nemichthys are shown in Table 3 and 

 Figure 4. The gross differences in the adults 

 of the four families are probably due to the 

 drastic changes undergone during metamorphosis 

 and other causes. At present, I can only point out 

 the similarities of the Cyemidae to the Sac- 

 copharyngiformes. Further studies may provide 

 information to help include or exclude the 

 Cyemidae in the Saccopharyngiformes. 



ACKNOWLEDGMENTS 



I thank Richard H. Rosenblatt of the Scripps 



Institution of Oceanography and Elbert H. 

 Ahlstrom of the National Marine Fisheries Serv- 

 ice, La Jolla, for critically reading the manu- 

 script. Joseph F. Copp checked the station data. 

 I am especially grateful to John D. Isaacs for his 

 encouragement and for the award of a postdoctoral 

 fellowship from his research funds during the 

 tenure of this work. I thank the authorities of 

 Simpson College for the assistance given in 

 finalizing this paper. This paper is a contribution 

 of the Scripps Institution of Oceanography. 



LITERATURE CITED 



Beebe, W., and J. Crane. 



1936. Deep-sea fishes of the Bermuda Oceanographic 



Expeditions. Family Serrivomeridae. Part I: Genus 



Serrivomer. Zoologica (N.Y.) 20:53-102. 

 1937a. Deep-sea fishes of the Bermuda Oceanographic 



Expeditions. Family Serrivomeridae. Part II: Genus 



Platuronides. Zoologica (N.Y.) 22:331-348. 

 1937b. Deep-sea fishes of the Bermuda Oceanographic 



Expeditions. Family Nemichthyidae. Zoologica (N.Y.) 



22:349-383. 

 Bertin, L. 



1934. Les poissons apodes appartenant au sous-ordre des 



Lyomeres. Dana Rep. Carlsberg Found. 3, 55 p. 

 1937a. Un nouveau genre de poissons apodes caracterise 



par I'absence de machoire superieure. Bull. Soc. Zool. 



Fr. 61:533-540. 

 1937b. Les poissons abyssaux du genre Cyema Giinther 



(anatomie, embryologie, bionomie). Dana Rep. Carls- 

 berg Found. 10, 30 p. 

 1938. Formes nouvelles et formes larvaires de poissons 



apodes appartenant au sous-ordre des Lyomeres. Dana 



Rep. Carlsberg Found. 15, 26 p. 

 Bohlke, J. E. 



1966. Order Lyomeri, Deep-sea gulpers. In Fishes of the 



western North Atlantic. Part Five, p. 603-628. Mem. 



Sears Found. Mar. Res. 1. 



Table 3. — Comparison of larval characters. 



561 



