FISHERY BULLETIN: VOL. 77, NO. 4 



petasma which in P. serrata, although thickened 

 mesially, does not form a sharp crest as it does in 

 P. rectacuta; by the proximal plate of the dorsolat- 

 eral lobule subrectangular in the former and 

 nearly circular in the latter; and by the apical 

 process of the ventral costa which is conspicuously 

 broader in P. serrata than in P. rectacuta. 



Remarks. — With reference to the types of this 

 species, both Bate (1881) and A. Milne Edwards 

 considered the account of P. serratus included in 

 the A. Milne Edwards' manuscript — later pub- 

 lished jointly by A. Milne Edwards and Bouvier 

 (1909) — to constitute the original description; 

 therefore, it seems reasonable to me that the syn- 

 types of this species, from Barbados, designated by 

 A. Milne Edwards and BouVier are, by implica- 

 tion, also those of Bate. Furthermore, Bate 

 (1881:180) stated that "I have not had an oppor- 

 tunity of examining the branchial apparatus to 

 feel quite certain that the genus [Penaeopsis] is a 

 good determination," thereby indicating that he 

 had not examined any specimens of P. serrata. 



Commercial importance. — Extensive explorations 

 in the Gulf of Mexico, the Caribbean, and along 

 the northern coast of South America by the U.S. 

 Government vessels Oregon and Oregon II dem- 

 onstrated the occurrence of megalops in many 

 areas on the upper slope of the continental and 

 insular shelves. It is common in many localities, 

 and, on the basis of collections made by the RV 

 Alaminos, Roberts and Pequegnat (1970) stated 

 that this shrimp "is the most abundant penaeid 

 caught by \he Alaminos in the Gulf, and it appears 

 to be most abundant in the De Soto Canyon around 

 200 fathoms [366 m] and, secondarily, off the Rio 

 Grande in 150 fathoms [274 m]." Even though it is 

 frequently taken while trawling for the royal red 

 shrimp, Pleoticus robustus (Smith 1885), Harvey 

 R. Bullis, Jr. (see footnote 4) has informed me that 

 no serious effort was made during the cruises of 

 the Oregon and Oregon II to assess the commercial 

 potential of P. serrata. The reason for lack of in- 

 terest in investigating possibilities for commercial 

 exploitations was the small size of this shrimp — 

 according to Bullis, the average count of megalops 

 tails would have been in the range of 60-100/lb 

 (132-220/kg). In the eastern Atlantic this species 

 constitutes a pairt of the commercial catches: 

 Maurin ( 1952) cited it as one of the shrimps com- 

 mercially fished off Morocco at depths >200 m; I 



have examined two females sorted by L. B. Hol- 

 thuis from commercial catches made by a Cadiz 

 trawler off Rabat, Morocco; and Holthuis and Rosa 

 ( 1965) listed it among the shrimps of economic 

 value in the "Southeast Atlantic Area." 



ACKNOWLEDGMENTS 



This study has been made possible through the 

 generous cooperation of many colleagues on four 

 continents who made available to me invaluable 

 collections. In addition, some of them provided 

 facilities for me to work at their respective institu- 

 tions. I am deeply indebted to Anthony A. Fin- 

 cham and Raymond W. Ingle (BMNH), Jacques 

 Forest (MP), and Lipke B. Holthuis (RMNH) for 

 placing at my disposal critical specimens and pro- 

 viding working space and encouragement. I am 

 also grateful to the following individuals for mak- 

 ing additional material available to me: Alan 

 Crosnier, Office de la Recherche Scientifique et 

 Technique Outre Mer , Paris; Antonio J. de Freitas 

 (ORI); Richard L. Haedrich, Woods Hole Oceano- 

 graphic Institution, Woods Hole, Mass.; Willard 

 D. Hartman (YPM); Boris G. Ivanov (VNIRO): 

 Brian Kensley (formerly SAM); Herbert W. Levi 

 (MCZ); Patsy A. McLaughlin (FIU); G. Ramak- 

 rishna(ZSI);P. Subramanian, Center of Advanced 

 Study in Marine Biology, Parangipettai; Krishna 

 Kant Tiwari (ZSI); and Gilbert L. Voss (UMML). 



Thanks are due Harvey R. Bullis, Jr., formerly 

 of the Southeast Fisheries Center, National 

 Marine Fisheries Service, NOAA, Miami, Fla., for 

 the graph of the depth-temperature relationship 

 and for his cooperation through the many years 

 during which he, in charge of the Oregon and Ore- 

 gon II, preserved and made available to me exten- 

 sive collections of penaeoids from catches of those 

 U.S. Gtovernment vessels. 



I am also indebted to my colleagues Horton H. 

 Hobbs, Jr. of the Smithsonian Institution for his 

 invaluable advice and critical comments during 

 the preparation of this work, and Fenner A. Chace, 

 Jr. and Raymond B. Manning, both of the Smith- 

 sonian Institution, for the review of the manu- 

 script and helpful suggestions. 



An important contribution to this study was the 

 cooperation of Maria M. Dieguez, who rendered 

 the detailed illustrations and assisted me in the 

 preparation of the lists of material. Finally, I am 

 grateful to Arleen S. McClain and Virginia R. 

 Thomas for typing the manuscript. 



760 



