HARVARD UNIVERSITY m LIBRARY OF THE Museum of Comparative Zoology urn ^®®iL(D(gir VOLUME 8 1960-1961 TULANE UNIVERSITY NEW ORLEANS TULANE STUDIES IN ZOOLOGY is devoted primarily to the zoology of the waters and adjacent land areas of the Gulf of Mexico and the Caribbean Sea. Each number is issued separately and contains an individual monographic study, or several minor studies. As volumes are completed, title pages and tables of contents are distributed to institutions exchanging the entire series. Manuscripts submitted for publication are evaluated by the editor and by an editorial committee selected for each paper. Contributors need not be members of the Tulane University faculty. MEMBERS OF THE EDITORIAL COMMITTEES FOR PAPERS PUBLISHED IN THIS VOLUME Stuart S. Bamforth, Tulane University, New Orleans, Louisiana Charles M. Breder, Jr., American Museum of Natural History, New York, New York Kenneth D. Carlander, Iowa State University, Ames, Iowa Dennis Chitty, Oxford University, Oxford, England Franklin C. Daiber, University of Delaware, Newark, Delaware Earl E. Deubler, Jr., Institute of Fisheries Research of the University of North Carolina, Morehead City, North Carolina Harold A. Dundee, Tulane University, New Orleans, Louisiana Gerald E. Gunning, Tulane University, New Orleans, Louisiana Horton H. Hobbs, Jr., University of Virginia, Charlottesville, Virginia H. B. Hungerford, University of Kansas, Lawrence, Kansas Robert F. Inger, Chicago Natural History Museum, Chicago, Illinois Theodore L. Jahn, University of California, Los Angeles, California James N. Layne, University of Florida, Gainesville, Florida Harold W. Manter, University of Nebraska, Lincoln, Nebraska Walter E. Martin, University of Southern California, Los Angeles, California George H. Penn, Tulane University, New Orleans, Louisiana Frank A. Pitelka, University of California, Berkeley, California Edward C. Raney, Cornell University, Ithaca, New York George K. Reid, Florida Presbyterian College, St. Petersburg, Florida Robert B. Short, Florida State University, Tallahassee, Florida Philip W. Smith, Illinois Natural History Survey, Urbana, Illinois Grover C. Stephens, University of Minnesota, Minneapolis, Minnesota Fred S. Truxal, Los Angeles County Museum, Los Angeles, California Ralph Wichterman, Temple University, Philadelphia, Penn.sylvania Satyu Yamaguti, United States Agricultural Research Center, Beltsville, Maryland M?. ZOOL] ARY JAN 25 1962 HA^.MRD iiuiurnoiTV CONTENTS OF VOLUME 8 NUMBER PAGE 1. STUDIES ON THE BACKSWIMMERS OF COSTA RICA (HEMIPTERA; NOTONECTIDAE) '. John L. DeAbate 3 2. THREE ASCOCTYLE COMPLEX TREMATODES (HETEROPHYIDAE) ENCYSTED IN FISHES FROM LOUISIANA, INCLUDING THE DESCRIP- TION OF A NEW GENUS Franklin Sogandares-Bernal and John F. Bridgman 31 AGE AND GROWTH OF THE SPOT, LEIOSTOMUS XANTHURUS LA- CEPEDE Bangalore I. Sundararaj 41 3. THE BREEDING HABITS OF THE MOLE SALAMANDER, AMBYSTOMA TALPOIDEUM (HOLBROOK), IN SOUTHEASTERN LOUISIANA C. Robert Shoop 65 SALINITY RELATIONS OF SOME FISHES IN THE ARANSAS RIVER, TEXAS William C. Renfro 83 4. ECOLOGY OF THE RICE RAT, ORYZOMYS PALUSTRIS (HARLAN), ON BRETON ISLAND, GULF OF MEXICO, WITH A CRITIQUE OF THE SO- CIAL STRESS THEORY Norman C. Negus, Edwin Gould, and Robert K. Chipman 95 5. A QUANTITATIVE STUDY OF THE MOVEMENT OF PARAMECIUM CAUDATUM AND P. MULTIMICRONUCLEATUM D. F. Sears, and Lila Elveback 127 NINE DIGENETIC TREMATODES OF MARINE FISHES FROM THE ATLANTIC COAST OF PANAMA Franklin Sogandares-Bernal and Lucy McAlister Sogandares 141 6. THE FEMALE REPRODUCTIVE CYCLE OF THE CRAYFISH CAMBA- RELLUS SHUFELDTI: THE INFLUENCE OF ENVIRONMENTAL FAC- TORS . Mildred Eileen Lowe 157 FECUNDITY AND REPRODUCTION IN THE LARGESCALE MENHA- DEN, BREVOORTIA PA TRONUS GOODE Royal D. Suttkus and Bangalore I. Sundararaj 177 PHnted in the U.S.A. at New Orleans, by Hauser Printing Co., Inc y - Nr. - ^%^ Oy/. (2:^/7^ Mus. po'"^ im fMY 1 0 1960 ^ARv m IWiVERSITY Volume 8, Number 1 April 29, I960 STUDIES ON THE BACKSWIMMERS OF COSTA RICA (Hemiptera; Notonectidae) JOHN L. DE ABATE, DEPARTMENT OF BIOLOGY, UNIVERSITY OF COSTA RIGA, SAN JOSE, COSTA RICA TULANE UNIVERSITY NEW ORLEANS TULANE STUDIES IN ZOOLOGY is devoted primarily to the zoology of the waters and adjacent land areas of the Gulf of Mexico and the Caribbean Sea. Each number is issued separately and contains an individual study. As volumes are completed, title pages and tables of contents are distributed to institutions exchanging the entire series. Manuscripts submitted for publication are evaluated by the editor and by an editorial com- mittee selected for each paper. Contributors need not be members of the Tulane Univer- sity faculty. 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George Henry Penn, Editor Meade Natural History Library, Tulane University, New Orleans, U. S. A. TULANE STUDIES IN ZOOLOGY Volume 8, Number 1 April 29, I960 STUDIES ON THE BACKSWIMMERS OF COSTA RICA (Hemiptera; Notonectidae) JOHN L. DE ABATE, Department of Biology, University of Costa Rica, San Jose, Costa Rica CONTENTS I. Introduction 3 II. Key to the Males of the Costa Rican Notonectidae 4 III. The Notonectidae of Costa Rica 5 A. Notonecta ceres ceres Kirkaldy, 1897 5 1 . Statistical analysis 6 2 . Li f e history 9 3. Growth 13 B. Notonecta indica Linne, 1771 16 C. Notonecta confusa Hungerford, 1930 18 D. Notonecta oc^ro//)o^ Kirkaldy, 1897 18 E. Buenoa eras sip es (Champion) Kirkaldy, 1904 19 F. Buenoa p aliens (Champion) Kirkaldy, 1904 , 19 G. Buenoa pallipes (Fabricius) Kirkaldy, 1904 21 H. Buenoa platycenemis (Fieber) Kirklady, 1904 21 I. Buenoa antigone antigone (Kirklady) Truxal, 1953 23 J. Buenoa gracilis Truxal, 1953 23 K. Buenoa ida Kirklady, 1904 ^ 23 IV. Geographic Variation in Buenoa 24 V. Acknowledgements 27 VI. References Cited 27 Abstract 28 EDITORIAL COMMITTEE FOR THIS NUMBER: H. B. HuNGERFORD, Professor of Entomology, University' of Kansas, Lawrence, Kansas George H. Penn, Professor of Zoology, Tulane University, New Orleans, Lou- isiana Fred S. Truxal, Curator of Entomology, Los Angeles County Museum, Los Angeles, California MUS. ''-' ZOOL MAY 10 1960 HARVARD HMVERSITY No. 1 DeAbate: Backswimmers of Costa Rica 3 I. Introduction region, varies from 18.8°C in January to a Although Costa Rica has a rich fauna, median maximum of 20.5 °C during May. studies of the insects are few. Some early The extremes range from 16.4°C to 28.1 °C. naturalists (Calvert, 1917; Champion, 1897- ^s the annual curve of temperatures reaches 1901; Picado, 1913; Pittier and Biolley, just one maximum and one minimum, the 1895; Pittier, 1942) pubhshed on various climate is considered of tropical type, species but, with the exception of a recent The hydrographic system of the Central work (Rosabal, 1954), there has not been Plateau area studied originates in the sur- any systematic attempt to study related forms rounding mountains, and runs through the at the generic or family levels. plains of the west coast to the Pacific Ocean. The only records of the Costa Rican The great majority of the rivers (Torres, Notonectidae are by Champion (1897-1901), Maria Aguilar, Tiribi, Carrizales, etc.) join Hungerford (1933), and Truxal (1953). to form a large stream bearing the name Rio After Hungerford's studies on the taxonomic Grande de Tarcoles. The rivers of the value of male genitalia in aquatic Hemiptera Plateau are not large and diminish during (1919b), Champion's work became obsolete ^^e dry season (December to May) but as it was based on external morphology and never become dry. During the rainy season pigmentation only. Hence, the only reliable ( May to November ) numerous temporary information is that of Hungerford and Trux- bodies of water are formed. These are im- al who reported six forms from occasional portant to the dispersal of the Notonectidae. collections. In the words of Hungerford: The other areas studied in this work (Rio ". . . surely there are species not yet recog- Sucio, Sarapiqui ) are in the lowlands north nized and more intense collecting and closer of the Central Plateau, and are irrigated by scrutiny will prove fruitful indeed " northward flowing streams that join the San In the course of this work, 2,357 speci- Juan River which empties into the Atlantic mens were studied, 697 specimens of the Ocean. The high mountains of the Cordil- genus Notonceta, and 1,660 of Buenoa. In lera Volcanica separate this region from the studying geographic variation in Buenoa. Plateau, leaving a few narrow passages. And many series from various countries were finally, the area of San Isidro de El General, examined. The material was obtained from in spite of being in the lowlands south of the Francis Huntington Snow Entomological the Plateau, has climatic and hydrographic Collections (FHSC) at the University of conditions very similar to the latter. Kansas, Museo Nacional de Costa Rica The vegetation of the Central Plateau is (MNCR), and the author's collection. transitional between basal and subalpine. In Areas studied. — Costa Rica, because of its the east and north, the Plateau is continued geographic location, is the meeting place of as lowland tropical rain forest; to the west the northern and southern faunas of the it is replaced by grassland prairies which hemisphere. Several species common to become deserts in the northwest part of the North and South America have not been country. To the south the Plateau is con- repoted in Costa Rica, but their presence is tinued in part by subtropical forest and anticipated. grasslands. Most of the Costa Rican material studied . Methods.— The methods and techniques was obtained from the Central Plateau and used in the dissection and clearing of geni- adjacent areas. talia, study of appendages, measurements The Central Plateau is a valley about and identification, follow those recommend- 1,000 M in altitude, bordered by mountains ed by Hungerford (1933) and Truxal to the north and south, and by lowlands (1953). Illustrations were made with the east and west. help of a camera lucida. Pubescence was The proximity of both Atlantic and Pa- omitted when it obscured characters of taxo- cific Oceans provides a relatively homo- nomic importance. geneous climate with such a minimum an- All measurements were made using an nual oscillation that the climate of the region ocular micrometer and reticule on a Bausch has been classified as insular ( Pittier, 1942). and Lomb stereoscopic microscope. In meas- The monthly median temperature for San uring the relative position of the curvature Jose, which is a good representation of the in the pronotum for Notonecta ceres ceres, Tulane Studies in Zoology Vol. 8 Fig^ures 1-2. Notonecta ceres ceres. 1. Meas- urements of pronotum : a = total length of side, b = distance from middle of curvature to anterior angle, c = distance from middle of curvature to posterior angle. 2. Genital capsule, lateral view. the scheme shown in Figure 1 was used. This computation is expressed in the graphs as a proportion which results from dividing the distance from the middle of the curva- ture to the anterior angle of the pronotum by the total length of the side of the pro- notum. Graph forms follow the methods of Hubbs and Hubbs (1953) with the exception of the small samples (less than 14) which were computed according to the method described by Cazier and Bacon (1949). II. Key to the Males of the Costa RlCAN Notonectidae ' 1. Hemelytral commissure with- out definite hair-lined pit at anterior end. Anterolateral margins of prothorax non- foveate (Notonecta) 2 1 This key was prepared by modification of Hungerford (193.3) and Truxal's (1953) keys and includes forms that have not been reported for Costa Rica, but are anticipated because of their distribution north and south of Costa Rica. Hemelytral commissure with definite hair-lined pit at an- terior end. Ventral abdomi- nal keel extending onto last abdominal segment. Males with anterior tai'si two-seg- mented (Buenoa) 5 2. Keel of fourth abdominal sternite bare, the hairs con- fined to the sides N. c. ceres Keel of fourth abdominal sternite not bare 3 3. Pronotum broad in front, em- bracing the eyes, which are flattened and receding from the anterior margin of the vertex. Synthlipsis broad, one half the anterior margin of vertex as seen from above. Scutellum distinctly broader than long. Males with stout tubercle at angle of front trochanter N. ochrothoe Pronotum not broad in front. Eyes not as above. Males without stout tubercle at angle of front trochanter - 4 4. Synthlipsis distinctly less than one half anterior margin of vertex; head prominent N. indica Synthlipsis wide, one half or more the anterior margin of vertex; head not prominent N. confusa 5. Synthlipsis wide, one half or more the anterior margin of vertex 6 Synthlipsis narrow, less than one half the anterior margin of vertex 10 6. Rostral prong with base origi- nating laterally at or near distal end of third rostral segment 7 Rostral prong with base not originating laterally at or near distal end of third ros- tral seg-ment 8 7. Over 7 mm in length. Prono- tum with its median length approximately three fifths its humeral width; disc al- most unimpressed, not tri- carinate B. crassipes Less than 7 mm in length. Pro- notum with its median length approximately two thirds its humeral width; disc with two elongate de- pressions toward the middle and a large subtriangular depression on each side, thus appearing distinctly tricari- nate B. pallipes 8. Posterior margin of hind fe- mur with more than forty setae in ventral row B. pallens Posterior margin of hind fe- No. 1 De Abate: Backswimmers of Costa Rica mur with less than forty setae in ventral row 9 9. Pronotum almost unimpressed, not tricarinate; length of fore femur two times the width of apex; approxi- mately twenty-five teeth in tibial comb B. ida Pronotum tricarinate; length of fore femur three times or more the width of apex; forty to fifty teeth in tibial comb B. ant {gone 10. Fore femur narrowed at apex; length more than three times the width of apex, the strid- ulatory area consisting of six to nine sclerotized ridges. Rostral prong equal to or shorter than third rostral segment B. gracilis Fore femur widened at apex; length three times or less the width of apex, the strid- ulatory area consisting of eleven to fourteen sclerotized ridges. Rostral prong much longer than the third rostral segment B. platycnemis III. The Notonectidae of Costa Rica A. Not one eta ceres ceres Kirkaldy, 1897 Synonymy- — 1897. N. mexicana var. ceres Kirkaldy, Trans. Ento. Soc. London, p. 402; 1933. N. ceres rogersi Hungerford, - For complete synonymy see : 1933. A^. c. ceres Kirkaldy; Hungerford, Univ. Kans- as Sci. Bull., 34(5) : p. 79. Figure 3. Localities from which Costa Rican Notonectidae were examined. 1 =: Sarapi- qui, 2 = Rio Sucio, 3 = Laguna Zarcero, 4 = La Palma, 5 = Laguna San Isidro, 6 = San Jeronimo, Moravia, 7 = Rio Torres, 8 = San Jose, 9 = Escazu, 10 = Rio Virilla, 11 = Rio Maria Aguilar, 12 = Rio Tiribi, 13 ^ Desamparados, 14 =^ Carrizales, Escazu, 15 = San Isidro de El General. Tulane Studies in Zoology Vol. 8 Bull. Univ. Kansas, 34(5): p. 81. The following description is modified from that of Hungerford ( 1933) to fit the ranges of variation found in the specimens that I studied. Size^ — Length, 10.4 mm to 12.7 mm; width of pronotum, 4.3 to 5.2 mm. Color. — Red and black or tan and black for females; males are typically black but I have found specimens in which red was present in various degrees. Color variations are described in section below on statistical analysis. Anterior half of pronotum, head and limbs yellow or yellowish green; the middle and hind trochanters and femora with the dark stripe of the N. mexicana Amyot and Serville group. Structural characters. — Head large; an- terior outline of head viewed from above, flattened; vertex a little longer than its anterior width; anterior margin of vertex less convex and plainly shorter than the frontal margin of the eye; anterior breadth of vertex: synthlipsis :: 11 : 3. Pronotum nearly twice the length of head; lateral margins moderately concave and moderately divergent; the margin more concave in fe- males than in males, as seen from the side, strongly curved, pronounced on anterior half; margin of prothorax shorter than the rear margin of the eye below it. Anterior lobe of membrane of hemelytra a little longer than the posterior one. Anterior trochanters of male with moderate hook. Mestotrochanters rounded. The carina of fourth abdominal sternite bare. The termi- nal abdominal sternite of female narrow, broader at the tip, and broadly incised. First pair of gonapophyses short. Male genital capsule as shown in Figure 2. Location of types. — Kirkaldy collection at U. S. National Museum, Washington. Comparative notes. — This subspecies was described by Hungerford (1933) as being different from N. c. rogersi. I have found that both are intergrades; a more detailed account is given in the statistical analysis. Geographic distribution and specimens studied (fig. 3). — San Jose: Aug. 1905, P. Biolley, 1 female, 1 male (FHSC). Rio Virilla: Dec. 1931, H. Schmidt, 9 females, 3 males (FHSC). Rio Tiribi: Aug. 1956, J. De Abate, 2 females, 7 males, 6 nymphs (002j;=* July 1957, J. De Abate, 6 females, 3 males (009); Desamparados: Feb. 1958, S. Jimenez-Canossa, 13 females, 7 males, 42 nymphs (016). San Rafael Escazu: Jan. 1957, S. Jimenez-Canossa, 3 females, 6 nymphs (003). Carrizales, Escazu: Oct. 1957, S. Jimenez-Canossa, 3 females, 1 male, 4 nymphs (012); Nov. 1957, S. Jimenez- Canossa, 5 females, 8 males, 8 nymphs (013); Nov. 1957, S. Jimenez-Canossa, 26 females, 46 males, 205 nymphs (014); Dec. 1957, S. Jimenez-Canossa, 19 females, 26 males, 88 nymphs (015). San Jeronimo, Moravia: July 1956, J. De Abate and L. Mata, 1 females, 3 males (001). La Palma: date unknown, Tristan, 1 male (MNCR); date unknown, P. Biolley, 1 female, 3 males (FHSC). Laguna San Isidro, Heredia: July 1957, J. De Abate and L. Ferrero, 13" fe- males, 13 males, 19 nymphs (008). Rio Sarapiqui: date unknown, H. Schmidt, 2 females, 2 males, 15 nymphs (FHSC). Rio Sucio: date unknown, H. Rogers, 1 female, 1 male (FHSC). Besides ceres this species has another sub- species, N. c. stirtoni, which has been re- ported only for El Salvador. 1 . Statistical analysis In his monograph on the Notonecta of the World, Hungerford (1933) described a new subspecies, N. c. rogersi.. The char- acters used in the description were: total 0:35 Son Isidro 0 40 0:45 0 50 I .^^^^ 4 9 Son Itldro Vlrlllo Eicozu Corrizoles 1 — 1 10 I II 12 ■T 13 3 _^^ Ln 1 ' Figures 4-5. Notonecta ceres ceres. 4. Posi- tion of the curvature at the side of pro- notum. 5. Total len^h variation in neigh- boring: populations. •' Numbers in parenthesis indicate cata- log number in writer's collection. No. 1 De Abate: Backswimmers of Costa Rica length, and relative position of the curvature at the sides of the pronotum. With respect to total length Hungerford established the limit at 12 mm, calling ceres the individual which were 12 mm or less in total length and rogersi those exceeding that limit. For the other character he wrote: ". . . The lateral margins of the pronotum of female constricted in front of the middle: rogersi . . .". ". . . The lateral margins of the pronotum of female constricted near the middle; ceres...". However as his arbitrary limit for total length does not correspond to that found in nature, and the description "near the middle" is rather vague, I have analyzed statistically both characters to de- termine the validity of the subspecific status. According to Hungerford's descriptions, only seven of the 64 specimens I studied for this purpose could be regarded as ceres and seven as rogersi. The rest (52 specimens) vary so much that they do not fit completely either description. Four samples were used in the statistical analysis: 8 specimens from Rio Virilla, 13 specimens from San Isidro de Heredia, 24 from Carrizales de Escazu and 19 from Escazu. In all cases the data refer to adult females, which were selected because they have the curvature more pronounced, and to avoid the introduction of error by using both sexes. Position of pronotal curvature. — The pop- ulations analyzed intergrade in such a man- ner that a subspecific status for this character becomes inconsistent ( fig. 4 ) . The samples from Rio Virilla, Escazu, and Carrizales ap- pear to be more closely related to one an- other than to the one from San Isidro. This perhaps can be correlated with geographic distribution, since the first three areas are about two miles apart, whereas the latter is about ten miles away. Total length. — Although total length is of little taxonomic significance, I attempted to find every possibility for segregation. Figure 5 shows an intergrading situation in which the Rio Virilla sample has higher values than the rest. This variance is not enough to justify a subspecific rank, and it is probably due to ontogenetic variation. Figure 6 is a scatter-diagram in which the values for the position of the pronotal curva- ture and total length have been plotted for PRONOTAL CURVATURE 0 37 0.43 0 49 0.5! ro — 1 — • 1 • • • 0 • o CJ - D + a • a o z o Oo K o D O ffl(+2) a UJ a 04-0 + -1 + + a + U) -t- -hU) _) "• n+ + • 4 1 < + DW a • o O 1 D D D □ 1 + 12) • • • Fig-ure 6. Notouecta ceres ceres. Total length compared with relative position of pronotal curvature. Crosses = Carrizales; squares ^ Escazu; small circles ^ Rio Virilla; black dots = San Isidro Heredia. 8 Tulane Studies in Zoology Vol. 8 all four samples. Here again we can see that there is not enough segregation of in- dividuals and that N. c^ ceres has a wide range of variation. Conclusions. — According to this analysis I feel that there is no reason for maintaining the subspecific status for N. c. rogersi, which I have relegated to synonymy with N. c. ceres. Color variation. — In males there is a gra- dation in color ranging from the typical black to almost red. This variation con- cerns only the clavus and corium; the scutel- lum and membrane are always black. The 114 specimens studied for this pur- pose were placed in five representative groups according to coloration (fig. 7). The incidence (by percent) in each group lU U CO Fi^re 7. Notonecta ceres ceres. Color variation in male hemelytra; upper row, dorsal aspect; lower row, lateral aspect. Red areas shown in white. No. 1 DeAbate: Backs ii'immers of Costa Rica is as follows: A B C D E 42.1 30.7 6.1 12.8 8.7 No significance was found in color vari- ation among different populations. I pre- sume that nutrition and amount of sunlight are the main factors acting on this second- ary sexual character. This presumption is based on the observation that male speci- mens reared in the laboratory are paler and have more red areas than those found in the field. 2. Life history N. c. ceres has been reported only for Costa Rica, where it is abundant, but noth- ing has been published on its life cycle. During the summer of 1957, I had the op- portunity to rear a sufficient number of specimens to observe the complete life his- tory of this insect in the laboratory. The insects used for this purpose were col- lected from San Isidro de Heredia and Rio Tiribi. Duration The life cycle from oviposition to the emergence of the adults requires an average of 65 days. This includes an average incuba- tion period of 20 days at room temperature (23°C±:3). The duration of each nymphal instar is from 9 to 11 days at the same temperature. Eggs Elongate oval in shape with ventral side flat (fig. 8). Average of 15 eggs measured were: length, 2.2 mm (2.05 to 2.30 mm); width, 0.99 mm (0.90 to 1.05 mm); height, 0.94 mm (0.75 to 1.0 mm). This is one of the largest Notonecta eggs known. During Figure 8. Eggs of Noto)iecta ceres ceres attached to stem of Elodea sp. Notice how close together the eggs were laid. the first days the eggs are pearly white, becoming cream colored later. The only ex- ternal sign of embryonic development is the appearance of two small red spots in dorsal cephalic position, which correspond to the eyes (fig. 8). At hatching the nymphs emerge from a dorsal slit in the egg. In the aquaria, eggs were glued to leaves and stems of Elodea sp. and to debris. Nymphal instars The nymphal instars are similar, the dif- ferences being mostly quantiative. As in the rest of the notonectids, there are five instars. (I). First instar (figs. 9, 14, 19, 24).— Size: length, 3.0 to 3-25 mm; width of body, 1.35 to 1.7 mm; width of head, 1.02 to 1.27 mm; vertex, 0.55 to 0.85 mm; synthlipsis, 0.35 to 0.475 mm. Mean values are given in Table 1. Color. — Limbs and abdomen transparent when newly hatched, becoming white hours later; hairs smoky; eyes red; sides of pro- notium and abdomen testaceous; rostrum and antennae testaeceous dark; venter and ab- domen light. Structural characters. — Ventral abdominal carina absent as in all first instars of noto- nectids. Antennae directed downward, three- segmented, basal segment very short ( fig. 19). Anteapical spine of intermediate femora not present ( fig. 24 ) . Tarsi one- segmented, ending in two large claws. (II). Second instar (figs. 10, 15, 20, 25). — Size: length, 3.85 to 4.3 mm; body width, 1.35 to 2.25 mm; head width, 1.4 to 1.62 mm; vertex, 0.40 to 0.62 mm; synthlipsis, 0.20 to 0.325 mm. Mean values shown in Table 1. Color. — General facies, white; eyes red- dish brown; posterior femora with faint darker zone along the middle, correspond ng to the stripe characteristic of the N. mexi- cana group. Structural characters. — Ventral abdominal carina present and marginated with smoky hairs. Antennae three-segmented, oriented as in adults, with a structure as shown in fig. 20. Intermediate femora with ante- apical spine moderately developed ( fig. 24 ) . Tarsi one-segmented, the posterior with two subequal claws. (III). Third instar (figs. 11, 16, 21, 26). — Size: length, 5.15 to 5.85 mm; width of body, 2.2 to 2.7 mm; width of head, 1.8 to 10 Tulane Studies in Zoology Vol. 8 C3 03 C -a c o C ^^^ ^^^ """""^^^ 1 / ^ ^^^ ©^ 03 CO . c CO "= ?^ S <;) .4-> ~ CO 05 CO n 3 etf No. 1 DeAbate: Backswimmers of Costa Rica 11 2.0 mm; vertex, 0.50 to 0.75 mm; synthlip- sis, 0.225 to 0.375 mm. Mean values shown in Table 1. Color. — General facies white; eyes red- dish brown, dorsum of abdomen with lateral smoky bands poorly defined. Base of, beak and beak dark testaceous. Limbs testaceous, middle trochanters, hind trochanters and femora with the typical markings of the N. mexicana group; but not as pronounced as in later instars. Structural characters. — Ventral abdominal carina long, with the hairs darker than in the preceding stage. Antennae located as in adults and with structure as shown in figure 21. Intermediate femori with a hook-like Figures 14-18. Notonecta ceres ceres. Ventral aspects of nymphal instars. 14. First instar. 15. Second instar. 16. Third instar. 17. Fourth instar. 18. Fifth instar. Verti- cal line beside each figure = 1 mm. 12 Tulane Studies in Zoology Vol. 8 Table 1. N. ceres ceres: extreme ranges and mean vahies (bold face) for m.easurements in the nymphal instars. Instar Specimens Measured Total Length Body Length Head Width Vertex Synthlipsis 1 2 3 4 5 5 15 15 15 15 3.0 -3.16-3.25 3.85-4.11-4.3 3.15-5.49-5.85 7.25 7.56-1.85 9.2 9.73-10.2 1..35-1..54-1.70 l.:!5-1.84 2.25 2.2 -2.46 2.7 3.2 3.38-3.5 4.2 4.57 5.1 1.02-1.19 1.27 1.40-1..52 l.t)2 1.8 -1.90 2.0 2.25-2.38-2..50 2.9 -3.0 3.1 0.55-0.675 0.85 0.40 0.482 0.02 0..'.0- 0.604 0.75 0.65-0.756-0.87 0.80-0.857 0.95 0..35 -0.405-0.475 0.20 -0.27 -0.325 0.225 0.308-0.375 0.30 -0.356 0.45 0.30 -0.36 -0.45 anteapical process (fig. 26). Tarsi one- segmented. Wing pads as shown in figure 14. (IV). Fourth instar (figs. 12, 17, 22, 27). — Size: length, 7.25 to 7.85 mm; width of body, 3.2 to 3.5 mm; width of head, 2.25 to 2.50 mm; vertex, 0.65 to 0.87 mm; synth- lipsis, 0.30 to 0.45 mm. Mean values shown in Table 1. Color. — White. Eyes dark brown. Dor- sum of abdomen with lateral markings as in third instar. Base of beak and beak tes- taceous, clypeus darker. Limbs testaceous, all trochanters with median longitudinal stripe; anterior, middle and posterior femora also with the typical stripe of the N. 7nexi- Fifjures 19-23. Nototiccta ceres ceres. An- tennae of nymphal instars. 19. First in- star. 20. Second instar. 21. Third instar. 22, Fourth instar. 23. Fifth instar. cana group. Structural characters. — Carina as in third instar. Antennae located as in the preced- ing stage, with srtucture as shown in figure 22. Intermediate femora with anteapical process straight and well developed, and with a small tubercular process in the middle of the posterior margin (fig. 27). Tarsi as in third instar. Wing pads well developed (fig. 12). (V). Fifth instar (figs. 13, 18, 23, 28). — Size: length, 9.2 to 10.2 mm; width of body, 4.2 to 5.1 mm; width of head, 2.9 to 3.1 mm; vertex, 0.80 to 0.95 mm; synthlip- sis, 0.30 to 0.45 mm. Mean values shown in Table 1. ■ Color. — White. Eyes dark brown. Dorsal abdominal markings as in the preceding instar but more distinct. Beak and base of beak as in fourth instar. Ventral aspect darker than in the preceding instars. Limbs as in fourth instar but with darker markings. Structural characters. — Ventral abdominal carina as in the two preceding instars but more pronounced. Eyes strongly confluent posteriorly (fig. 13). Intermediate femora as in fourth instar but with processes more pronounced (fig. 28). Tubercular process in the middle of posterior margin more de- veloped than in the preceding instar. An- tennae located as in adults with a constric- tion in distal third of the third segment. In cleared and mounted antennae, a thin trans- verse septum can be seen near the level of the constriction (fig. 22) which will be- come the division between the third and fourth antennal segments of the adult. Wing pads extending beyond posterior thoracic border ( fig. 13). Mating When collected, many individuals were mating and they continued doing so after transferal to aquaria. This species is able to copulate three times per day, sometimes for periods of three continuous hours (maxi- No. 1 DeAbate: Backstvimmers of Costa Rica 13 Table 2. A^. c. ceres : monthly incidence of the various instars. Months J F M A M J J A S 0 N D 1 + + + + + + m 2 + + + + + + + (4 3 + + + + + + + + + 03 C 4 + + + + + + + + + + hH 5 + + + + + + + + + + + Ad. + + + + + + + + + + + + mum mating time observed was 3 hrs., 20 minj. For N. borealis Rice (1954) reported that, after mating, there is a preoviposition period. Nothing of this sort was observed in N. c. ceres, as females were actively mating dur- ing the oviposition period, sometimes lay- ing eggs just a few minutes after copulation. Seasonal activity In all months when collections were made, both adults and nymphs of various instars were found. The stages found and the months involved are given in Table 2. I presume that, due to the favorable cli- matic conditions of Costa Rica, N. c. ceres is able to breed the year around. Oviposition My laboratory notes read as follows "... A gummy substance is secreted on the surface where the eggs is going to be laid. The egg is held by ovopositor against the gummy substance until it is secure. All the process takes about 25 seconds for each egg...". Eggs are laid in an irregular manner. One isolated female laid 37 eggs in 13 days; that is, an average of 2.8 eggs per day. Four other females laid 76 eggs in 17 dags. 3. Growth To obtain estimates of growth rates, nymphs of the five instars were used. The distinct size groups corresponding to each instar are given in Table 1. For every measurement the mean, maximum, and minimum ranges of variation are given. For total length, body width, and head width there is a close isometric relationship. This is not true for the vertex and synthlipsis values where an apparent decrease in growth is detectable at the second instar. This can be explained not as a reduction of vertex and synthlipsis, but as a rapid growth of the eyes in molting to the second instar. The relative size of the eyes can be seen in figures 9, 10, 14, 15. Differential growth between males and females is not given, as sexual determination is difficult during the nymphal instars and the technic involved destroys the specimens. In checking Dyar's Law (1890) in an attempt to establish a definite growth rate for N. c. ceres, I found that if a measure- ment of the first nymphal instar was multi- plied successively by 1.3, and again this number by 1.3 a series of figures was ob- tained that corresponded closely to the values for that particular measurement in the different instars. Table 3 shows these theoretical values compared with the actual averages ( taken from Table 1 ) . In all cases the theoretical figures follow closely the actual values. Knowing the first instar, the measure- ments of other instars can be foreseen by using the equation: Y = M(1.3)N-i Where Y = the measurement of the nymph- al instar sought; M := same measurement in the first instar; 1.3^ the growth factor; and, N = the number of the instar sought in Y. A further attempt was made to determine the possibility of a unique growth rate, of the measurements studied for all notonectids. For this, data of head width published by Hunger ford (1919a) for N. undulata, N. irrorata and Buenoa margaritacea were used. Also data for N. insulata, N, borealis, N. raleighi and B. limnocastoris were taken from Rice (1942, 1954). Actual values were compared with the corresponding theo- retical figures ( Tables 4, 5 ) , and here again the growth rate factor of 1.3 is appropriate. Plotting these figures (figs. 29-32) shows that the theoretical figures follow closely the 14 Tulane Studies in Zoology Vol. 8 Figures 24-28. N o\onec\a ceres cerefs. Middle femora of nymphal instars. 24. First in- star. 25. Second instar. 26. Third instar. 27. Fourth instar. 28. Fifth instar. actual values for N. c. ceres, N. insulata, and fifth instars are very close, but not N. undulata, N. irrorata and B. margaritacea. those for the second and fourth. In N. bore- This is not so for the rest of the species alis and appreciable difference of values can studied. For N. raleighi the values for third be seen in the fourth instar. And finally, No. 1 DeAbate: Backsivimmers of Costa Rica 15 Table 3. A^ c. ceres: the actual and theoretical values of growth rate for body parts. Instar Body Len^h Actual 1.3 Body Width Actual 1.3 Head Width Actual 1.3 1 3.16 1.54 1.19 2 4.11 4.11 1.84 2.0 1.52 1.55 3 5.49 5.34 2.46 2.60 1.9 2.01 4 7.56 6.94 3.38 3.38 2.38 2.61 5 9.73 9.03 4.57 4.41 3.0 3.40 Table 4. Head width: theoretical and actual groivth rate values in five species of Notonecta. Instar N. un Actual dulata 1.3 A^. irrorata Actual 1.3 N. borealis Actual 1.3 N. insulata Actual 1.3 A^. raleighi Actual 1.3 1 0.833 0.91 1.045 1.092 0.532 2 1.06 1.083 1.2 1.18 1.375 1.358 1 1.419 0.95 0.691 3 4 1.4 1.87 1.41 1.833 1.56 2.08 1.54 2.0 1.815 1.766 1.935* 2.295 1.85 2.3 1.845 2.399 0.97 0.899 1.3 1.169 5 2.5 2.382 2.86 2.6 2.805 2.984 2.86 3.118 1.5 1.519 In Rice (1954) this value is reported as ".935", and is probably an error. for B. limnocastoris a considerable differ- ence is noted in the figures for second and fourth instars. In the last three cases Rice, who probably obtained the material from field collections and not from laboratory rearing, must have confused some nymphal instars, introducing variations of such magnitude as shown in the curves (figs. 30-32). Clark and Hersh (1939) studied the growth of N. undulata; theirs is a thorough study referring, specially, to growth centers and growth gradients. Applying the 1.3 growth rate factor to their data on head width and body length I found that it corresponded with deviations comparable to those cited in Table 4. Based on these data, I postulate that the growth rate of body length and head width is very close for all notonectids, if not the same. Further investigation of other species is necessary to establish a generalization in this respect. Food. — N. c. ceres, as the rest of the notonectids, has predaceous habits and prob- ably feeds on a great variety of animal forms. In nature I have seen it feeding on Buenoa and ostracods. In the laboratory it was fed on muscid flies {Musca sp. ), tab- anid flies (Tabanidae), mosquito larvae (Culex sp. ), stingless bees (Meliponidae), leaf hoppers (Jassidae) and on small snails (Tropicorbis sp. ), all of which were ac- cepted eagerly. I also observed that this species attacks and feeds on small fishes {Rivulus sp. ) and tadpoles (Hyla sp. ). When specimens were starved, cannibalism was observed. Behai'ior. — Adults are clumsy swimmers and spend most of the time "hanging" from the surface of the water. When feeding they hold their prey with their front legs, the middle legs hanging with claws just reach- ing the water surface, and the hind legs with femur and tibia at an angle of about 90° to each other. When attached to objects under water, they come to the surface to replenish air periodically. Air is stored under the heme- lytra and in the ventral abdominal pubes- cence. The average submergence time, taken from 20 observations, was 4 min., 15 sec, (26 sec. to 4 min., 35 sec), although Ed- wards (1953) reported that Notonecta are able to remain submerged up to six hours depending on the metabolic rate. Ecology. — In all cases N. c. ceres was collected in fresh water. This species was found most commonly in clear, slow-run- ning, permanent, shaded water. In most of the cases, the vegetation was moderate and a sandy-mud bottom was present. For the 16 Tiilane Studies in Zoology Vol. 8 cr UJ I- UJ 2 2 9 < LU X INSTARS Figure 29. Theoretical and actual growth rates for Notonecta ceres ceres and Notonecta insulata. Solid lines ^ actual values; broken lines ^ theoretical values. Actual data for second instar of N. insulata were unavailable. numerical incidence of each ecological situ- ation see Table 6. In respect to the fauna, Gerridae, Belosto- matidae, ostracods and small fishes and tad- poles were present in various numbers, and I assume that they play an important role in the biology of the notonectids. Notonetca indica Linne, 1771 Synonymy} — 1771. N. indica Linnaeus. Mantissa Plantarum, II, p. 534. Size. — Length, 10 mm to 11 mm, width ^ For complete synonymy see: 1933. No- tonecta indica Linne; Hungerford, Univ. Kansas Sci. Bull., 21(9) : p. 113. No. 1 De Abate: Backswimmers of Costa Rica 17 of pronotum, 3.36 to 3.75 mm. Color. — Luteous to almost black, heme- lytra usually white with base of clavus black or tan. Scutellum black, often pale at the tip and basal angles. Structural characters. — Head prominent, more than one half length of pronotum. Anterior margin of vertex straight; width of vertex: synthlipsis : : 5 : 2. Synthlipsis less than one half the anterior margin of the eye. Anterior angles of pronotum em- bracing the eyes. Anterior trochanter of male with a stout hook. Mesotrochanters rounded or nearly so. Male genital capsule not digitate and with claspers broad; incised at the tip. Geographic distribution. — This species has never before been reported for Costa CO q: UJ 1- LlI i 2 _i -J 2 X Q ? < UJ I INSTARS Figure 30. Theoretical and actual growth rates for Xotonecta borealis and Notouecta irrorata. Observe how closely the theoretical values follow the actual values, except for the fourth instar of N. borealis. Symbols as in figure 29. 18 Tidane Studies in Zoology Vol. 8 Rica. I collected one male specimen in the San Isidro Heredia Lagoon. In spite of a careful search, I was not able to find another specimen. Reports on the geographic distribution of this species give a range from 37° latitude in the United States to Brazil in South America. The reports for localities are as follows: United States, Mexico, Guatemala, Colombia, Brazil, and the islands of Cuba, Jamaica, St. Croix, St. Thomas and Puerto Rico. The Costa Rican specimen bears the following data: Costa Rica: Heredia, Laguna de San Isidro, J. De Abate and L. Ferrero, 1 male (008). This specimen was collected in fresh still water, in a shady area where vegetation was abundant. C. Notonecta conjusa Hungerford, 1930 Synonymy. — 1930. N. conjusa Hunger- ford. Bull. Brooklyn Ent. Soc. XXV, p. 140; 1933 N. conjusa Hungerford; Univ. Kansas Sci. Bull. 34(5): 1-195. Size. — Length, 12 mm; width of thorax, 4 mm. Color. — Pale yellow. Hungerford (1933) stated that the typical color is probably black and white. Structural characters. — This species is very similar to N. undulata Say, from which it 1.5 differs in having the mesotrochanter feebly angulate and the male genital claspers bi- furcate. This species was described from a single specimen. Geographic distribution. — The type local- ity is "South America"; another specimen was reported also from Cuba; I suspect that this species is present in Costa Rica. D. Notonecta ochrothoe Kirkaldy, 1897 Synonymy. — 1897. N. shoot erii var. ochrothoe Kirkaldy, Trans. Ent. Soc. London, p. 407; 1905. N. shooterii var. ochrothoe Kirkaldy; Bueno, J. N. Y. Ent. Soc, xiii, p. 161; 1933. N. ochrothoe Kirkaldy: Hunger- ford, Univ. Kansas Sci. Bull., 34(5), p. 99. Size. — Length, 10.8 to 11.4 mm; width of pronotum, 4.0 to 4.4 mm. Color. — Luteous or pale luteous. Structural characters.. — Anterior outline of the head viewed from above, convex; an- terior width of vertex: synthlipsis : : 3 : 2. Pronotum more than twice the length of head; anterolateral margins acute and em- bracing the eyes. Anterior trochanter of male with stout hook and tuberculate pro- jection on the basal angle. Mesotrochanters rounded. Male genital capsule with a thickened protuberance on keel. Geographic distribution. — This species hss not been reported for Costa Rica, but tn I- UJ X I- 9 Q 12 3 4 5 INSTARS Figure 31. Theoretical and actual g:rowth rates for Buenoa margaritacea and Buenoa limno castor is. Compare the clo.sely similar rates in B. margaritacea with deviations in B. limnocastoris. Symbols as in figure 29. No. 1 De Abate: Backswimmers of Costa Rica 19 its presence is anticipated. It has been re- ported from Colombia, S. A. and California, U. S. A. E. Buenoa crassipes (Champion) Kirkaldy, 1904 Synonymy.^ — 1901. Anisops crassipes Champion. Biologia Centrali - Americana, Heteroptera, vol. II, p. 374. Size. — Male, length 7.0 to 8.4 mm; head width, 1.75 to 2.2 mm; vertex 0.26 to 0.35 mm; synthlipsis, 0.10 to 0.21 mm. For the female Truxal ( 1953) reports the following figures: length, 5.98 to 7.5 mm; greatest body width, 1.75 to 2.01 mm. Color. — General fades testaceous to nigro- violaceous. Head, pronotum, venter and limbs testaceous. Keel and portions of conexivum testaceous. This species is vari- able in color. Male structural characters. — Viewed from above, head is laterally rounded with vertex indented. Greatest width of head from six to seven times the width of vertex. Synth- lipsis approximately half the width of ver- tex. Tyius slightly inflated. Rostral prong with apex rounded, its origin near the distal end ot third rostral segment. Fore femur with triangular and subtriangular stridula- tory area tormed by ten to eighteen ridges. Genital claspers normal. Female structural characters. — Head shaped as in males, five and one half times the width of vertex. Synthlipsis approximately one half the width of vertex. Scutellum with median length greater than that of pro- Table 5. Head width: theoretical and actual growth rate values in two species of Buenoa. B. limno castoris B. tnargaritacea Instar Actual 1.3 Actual 1.3 1 0.45 0.5 2 0.715 0.546 0.625 0.65 3 0.715 0.709 0.832 0.845 4 1.04 0.923 1.063 1.098 5 1.15 1.199 1.365 1.428 notum. Ovipositor normal in shape, with teeth arranged in two longitudinal rows. The inner row with large teeth, the outer row with smaller teeth. Geographic distribution. — This species has been reported for Guatemala, Costa Rica, Ecuador and Brazil. Specimens from the following localities were studied: Costa Rica: Heredia, Laguna Zarcero La Pena: Jan. 1957, J. Vieto, 6 females, 14 males, 5 nymphs ( 004 ) ; Laguna San Isidro, Aug. 1957, J. De Abate, 2 females, 10 males, 27 nymphs (008). San Jose; pur- chased June 1931, H. Schmidt, 20 females, 6 males (FHSC); June and July 1931, H. Schmidt, 11 females, 10 males (FHSC); purchased 1932, H. Schmidt, 82 females, 58 males (FHSC); Rio Virilla, Dec. 1931, H. Schmidt, 33 females, 21 males (FHSC); Rio Torres, Feb. 1932, H. Schmidt, 1 fe- male, 1 male, 1 nymph ( FHSC ) ; Heredia, Rio Sarapiqui, H. Schmidt, 8 females, 8 males (FHSC). Brazil: Sta. Catarina, Nova Teutonia, Dec. 1946, F. Plaumann, 20 females, 34 males (FHSC); Nova Teutonia, May 1948, F. Plaumann, 42 females, 23 males (FHSC). Ecology. — B. crassipes was found in fresh, clear, static, permanent, exposed waters. The incidence of this species in waters com- pletely exposed to the sun perhaps can be explained studying their behavior. These notonectids spend most of their time swim- ming gracefully or resting about four inches below the water surface, thus posibly having protection from the sun. F. Buenoa pallens (Champion) Kirkaldy, 1904 Synonymy.''' — 1901. Anisops pallens Champion. Biologia Centrali - Americana, Heteroptera, Vol. II, p. 374. Size. — Male: total length, 5.6 to 7.3 mm; head width, 1.4 to 1.9 mm; vertex, 0.23 to 0.37 mm. Truxal (1953) reports the fol- lowing figures for the female: length, 5.98 to 7.15 mm; greatest body width, 1.75 to 2.01 mm. Color. — Pale testaceous to nigro-violace- ous. Light specimens with ventral keel and last two segments testaceous. Dark speci- ments with head, anterior pronotum, venter and limbs testaceous. Scutellum usually black with apex testaceous or sordid white. This species is variable in color. Male structural characters. — Viewed from ■'For complete synonymy see: 1953. 6 Por complete synonymy see: 1953: Buenoa crassipes (Champion) ; Truxal, Buenoa pallens (Champion) ; Truxal. Univ. ,Univ. Kansas Sci. Bull., 35(11) : p. 1385. Kansas Sol. Bull., 35(11) ; p. 1414. 20 Tulane Studies in Zoology Vol. 8 12 3 4 5 INSTARS Figure 32. Theoretical and actual growth rates for Notojiecta iinclulata and Xotoiwcta raleighi. Observe closely similar actual and theoretical rates for N. inidnhtta; note the discrepencies in second and fourth instars of A'', raleighi. Symbols as in figure 29. above, head laterally rounded with vertex indented. Greatest width of head less than seven times the width of vertex. Synthlip- sis narrow, about three fifths the anterior width of vertex. Tylus slightly inflated; rostral prong variable in shape, its origin not at the distal end of the third rostral segment. Fore femur with triangular or sub- triangular stridulatory area formed by six- teen to twenty-two ridges. Genital claspers normal. Female structural characters. — Head shaped as in males, its width approximately five and one-half times the width of vertex. Synthlipsis approximately one-half the width of vertex. Scutellum large, with median length greater than the length of pronotum. Ovipositor normal in shape, with the teeth arranged in two rows. The inner row of few large teeth; the outer row of smaller teeth. Geographic distrih/ztion. — B. pallens has been recorded for Mexico, Guatemala, Costa Rica, St. Thomas, St. Croix, Guadeloupe, Dominica, Grenada, Trinidad, Colombia, Ecuador, Brazil, Peru and Chile. Specimens from the following localities were studied: Mexico: Morelos, Cuernavaca, Oct. 1936, H. D. Thomas, 126 females, 40 males (FHSC). Oaxaca, Aug. 1937, H. D. Thomas, No. 1 De Abate: Backswimmers of Costa Rica 21 30 females, 11 males (FHSC). as in males, its width about six times the Costa Rica: San Jose, Maria Aguilar, Oct. width of vertex. Synthlipsis as in males. 1957, S. Jimenez-Canossa, 7 females, 8 Scutellum large, its median length greater males, 1 nymph (Oil); Carrizales, Escazu, than that of pronotum. Ovipositor normal Oct. 1957, S. Jimenez-Canossa, 31 females, in shape, with teeth arranged in two lateral 26 males, 22 nymphs (012); Carrizales, rows. The inner row with large teeth, the Escazu, Oct. 1957, S. Jimenez-Canossa, 6 outer row with smaller teeth, females, 3 males, 4 nymphs (0.14); Carri- Geographic distribution. — B. pallipes has zales, Escazu, Dec. 1957, S. Jimenez-Canossa, been reported for Hawaii, Mexico, Hondu- 4 females (015). ras, Costa Rica, Panama, Jamaica, Puerto St. Croix: Christiansted, June 1941, H. A. Rico, St. Thomas, Guadeloupe, St. Vincent, Beatty, 1 female, 3 males ( FHSC ) . Colombia, Peru and Paraguay. I had the Peru : Cajamarca, Celendin, May and June opportunity of studying specimens from the 1936, F. Woytkowsky, 127 females, 117 following localities: males (FHSC); Amazonas, Chachapoyas, Honduras: Tela, Apr. 1923, J. Deal, 93 Aug. 1936, F. Woytkowsky, 36 females, 44 females, 76 males (FHSC). males (FHSC). Jamaica: Montego Bay, Lumsden Tyden- Ecology. — Specimens of this species were ham, St. Ann, Feb. 1928, L. G. Perkins, 7 found more commonly in fresh, clear, static, females, 3 males ( FHSC ) ; Baron Hill Tre- permanent, shaded waters. For the numeri- lawny, Feb. 1928, L. G. Perkins, 1 female, cal incidence of each ecological character see 1 male (FHSC); Bath St. Thomas, Mar. Table 4 1937, Ch. Roys, 19 females, 8 males (FHSC). G. Buenoa palhpes (Fahncms) q^^^^ rj^^. Cartago, San Isidro de El Kirkaldy, 1904 General, Feb. 1939, D. L. Rounds, 1 fe- Synonymy? — 1803. Notonecta pallipes male, 1 male (FHSC). Fabricius. Systema Rhyngotorum, p. 103. Peru: Amazonas, Guayabamba, Aug. Size. — Male: total length, 5.3 to 6.8 mm; 1936, F. Woytkowsky, 70 females, 67 males head width, 1.4 to 1.7 mm; vertex, 0.20 to (FHSC). 0.30 mm; synthlipsis, 0.09 to 0.15 mm. For Paraguay: Villarrica, Dec. 1924, F. the female Truxal ( 1953) gives the follow- Schade, 28 males (FHSC). ing figures: length, 5.62 to 6.50 mm; great- Ecology. — No data on the ecology of this est body width, 1.69 to 1.95 mm. species is available. I have not been able to Color. — Sordid white to black. Pronotum collect it although it was recorded from usually fuscous; scutellum black or fuscous, Costa Rica by Truxal (1953). with apex testaceous. Abdomen black ex- u d ^i . ■ / c- u \ , ^ , 1 . J • L Iri. Buenoa platycnemis ( Fieber ) cept for ventral keel and portions of co- J^ i a-^^ nexivum. This species is variable in color, Iruxal, 195:) a wide color gradation being found within Synonymy^ — 1851. Anisops platycnemis a single population. Fieber. Abhandlungen Kongl. Bohmishen Male structural characters.— ViQ^ed from Gesellschaft Wissenschaften, Vol. VII, Se- above, outline of head laterally rounded, its ^i^s 5, p. 485. width six times the width of vertex. Synth- Size. — Male: total length, 4.4 to 5.8 mm; lipsis narrow, approximately one-half the head width, 1.1 to 1.4 mm; vertex, 0.19 to width of vertex. Tylus inflated; rostal prong 0.28 mm; synthlipsis, 0.06 to 0.14 mm. with posterior margin almost straight, its Truxal (1953) reported the following meas- base originating at distal end of third rostral urements for the female: length, 5.00 to segment. Fore femur with a subtriangular 5.43 mm; greatest body width, 1.49 to 1.75 stridulatory area consisting of approximately mm. seventeen ridges. Male genital claspers Color. — Sordid white to black. Head, normal. parts of pronotum, thoracic venter and limbs Female structural characters. — Head shaped sordid white to testaceous. Scutellum usually ' For complete synonymy see : 1953. ^ For complete synonymy see : 1953. ^MeTioa paMipes (Fabricius) ; Truxal, Univ. Biienoa platycnemis (Fieber); Truxal, Kansas Sci. Bull., 35(11) : p. 1418. Univ. Kansas Sci. Bull., 35 (11) : p. 1421. 22 Tulane Studies in Zoology Vol. 8 testaceous or black with apex lighter. Ab- dominal venter black with keel and parts of conexivum testaceous. Male structural characters. — Viewed from above, head laterally rounded. Greatest width of head five to six times the width of vertex. Synthlipsis narrow, less than one-half the width of vertex. Tylus moderately inflated; rostral prong longer than third rostral seg- ment and originating at distal end of the third rostral segment. Fore femur with sub- triangular stridulatory area formed by eleven to fourteen ridges. Genital claspers normal. Female structural characters. — Head shaped as in males, its width five to five and one half times the width of vertex. Synthlipsis less than half the width of vertex. Scutellum large with median length greater than that of pronotum. Ovipositor of normal shape with teeth arranged in two rows; the inner row of large teeth, the outer row of small ones. Geographic distribution. — This species has been reported for the United States (Texas and Florida), Mexico, Cuba, Grand Cayman, Haiti, Jamaica, Mona, Puerto Rico, St. Thomas, St. Croix, Martinique, Costa Rica, Panama, Colombia, Venezuela, Brazil and Peru. Specimens from the following localities were studied: Mexico: Sonora, Rio Mayo, Feb. 1935, H. E. Gentry, 19 females, 8 males (FHSC). Michoacan, El Sabino Uruapan, July 1936, H.D.Thomas, 19 females, 19 males (FHSC). Campeche, Hda. Encarnacion, Oct. 1936, H. D. Thomas, 5 females, 6 Males (FHSC). U. S. A.: Texas, Mc Allen, Nov. 1932, L. D. Tuthill, 4 females, 6 males, (FHSC); Star Co., July 1938, R. I. Sailer, 5 females, 7 males ( FHSC ) ; Falfurrias, Jan. 1946, L. D. Beamer, 2 females, 2 males ( FHSC ) . Florida: L. Matecumba Key, Mar. 1947, R. H. Beamer and L. D. Beamer, 6 females, 5 males ( FHSC ) . Grand Cayman: Cow well near Pedro Castle, Oxford Univ. Biol. Exp., Aug. 1928, Lewis and Thompson, 11 females, 11 males ( FHSC ) . Cuba: Habana Bot. Garden, Jan. 1932, P. J. Bermudez, 8 females, 6 males (FHSC) ; Habana, 1933, P. J. Bermudez, 14 females, 31 males (FHSC). Puerto Rico: Luquillo July 1932, J. Blanch, 1 female, 2 males (FHSC); Que- brada, Feb. 1935, J. G. Diaz, 2 females, 1 male (FHSC); Florida Road, Feb. 1935, J. G. Diaz, 10 females, 5 males (FHSC); Table 6. Ecological data. N. c. ceres Buenoa crassipes B^ lenoa pa liens N. indica Number of collection sites 15 2 5 1 Abundant 20% Moderate 80% 100% 20% 80% 100% o M Sand 13.3% 50% Mud 20 % 20% Sandy mud 66.6% 50% 80% 100% Dark Clear 20% 80% 100% 20% 80% 100% %4 Flowing Static 53.3% 46.7% 100% 40% 60% 100% C5 Temporary Permanent 26.7% 73.3% 100% 40% 60% 100% Shaded Exposed 73.3% 26.6% 100% 60% 40% 100% No. 1 De Abate: Backs wimmers of Costa Rica 23 Almirante Road, March 1935, J. G. Diaz, 8 females, 5 males ( FHSC ) ; Tortuguera L., Mar. 1935, J. G. Diaz, 8 females, 3 males (FHSC); Near Isabela, May 1935, J. G. Diaz, 2 females, 7 males (FHSC); Luquillo Mts., Nov. 1935, J. G. Diaz, 8 females, 4 males (FHSC). Costa Rica: Cartago, San Isidro de El General, Feb. 1939, D. L. Rounds, 1 female, 4 males (FHSC). Colombia: Villavieja, 1944, R. A. Sdrton, 26 females, 22 males (FHSC). Peru: Amazonas, Vic. Guyabamba, Aug. 1936, F. Woytkowsky, 23 females, 28 males ( FHSC ) ; San Martin, Vic. Rioja, Sept. and Oct. 1936, F. Woytkowsky, 11 females, 11 males (FHSC). Ecology. — There are no reports on the ecology of this species. Only five specimens have been collected in Costa Rica and they bear no ecological data. I have not been able to collect this species. I. Buenoa antigone antigone ( Kirkaldy ) Truxal, 1953 Synonymy.^ — 1899. Anisops antigone Kirkaldy, G. W. The Entomologist, vol. XXXII, p. 30. Size^ — Male: length, 7.80 to 7.99 mm; greatest body width, 2.46 to 2.60 mm; fe- male: length, 8.25 to 8.51 mm; greatest body width, 2.60 to 2.79 mm. Color. — Testaceous; scutellum usually ochraceous, brown at the base. Ventral ab- domen brown or black with conexivum testaceous. Male structural characters. — Head laterally rounded when viewed from above, its width more than six times the width of vertex. Synthlipsis one half to two thirds the width of vertex. Rostral prong originating laterally at proximal end of third rostral segment. Fore femur with triangular stridulatory area consisting of fifteen to twenty-three ridges. Genital claspers normal. Females structural characters. — Head as in males. Synthlipsis more than half the width of vertex. Ovipositor with two rows of teeth all small except for the apical four in the outer row. Geographic distribution. — Recorded from ^ For complete synonymy see: 1953. Buenoa antigone antigone (Kirkaldy) ; Truxal, Univ. Kansas Sci. Bull., 35 (11): p. 1376. Mexico, Guatemala, Cuba, Grand Cayman, Haiti, Jamaica, Puerto Rico, St. Croix, Brazil, Ecuador, Peru, Bolivia, Paraguay and Argentina. Because of the recorded geo- graphic distribution, the presence of this species in Costa Rica is expected. J. Buenoa gracilis TtuxA, 19^0 Synonymy. — 1953. Buenoa gracilis Truxal, Univ. Kansas Sci. Bull. XXXV(ll), p. 1439. Size. — Male: length, 5.39 to 6.04 mm; greatest body width, 1.30 to 1.49 mm; fe- male: length, 5.52 to 6.11 mm; greatest body width, 1.36 to 1.69 mm. Color. — Sordid white. Abdominal venter black except keel and portions of conexivum, sordid white to pale testaceous. Male structural characters. — Viewed from above, outline of head laterally rounded; greatest width of head, six to six and one half times the width of vertex. Synthlipsis narrow, approximately one-fourth the width of vertex. Tylus inflated; rostral prong originating near the proximal end of third rostral segment. Fore femur with subtri- angular stridulatory area consisting of about six to nine ridges. Male genital claspers normal. Female structural characters. — Head shaped as in males, its width approximately five times the width of vertex. Pronotum faintly tricarinate; scutellum with median length greater than that of pronotum. Ovipositor normal in shape, with two rows of teeth; the inner row of large teeth and the outer row of smaller teeth. Geographic distribution. — Reported from Mexico, Honduras, Panama, Cuba, Jamaica, Puerto Rico, St. Croix, Grenada, and Peru. This species is probably present also in Costa Rica. K. Buenoa ida Kirkaldy Synonymy. — 1904. Buenoa ida Kirkaldy, G. W., Wiener Ziet., Vol. XXIII, pp. 121, 122 and 134; 1909- Buenoa ida Kirkaldy, G. W. and Torre-Bueno, J. R. de la. Proc. Ent. Soc. Washington, vol. X, p. 200. (cata- logue); 1953. Buenoa ida Kirkaldy; Truxal. Univ. Kansas Sci. Bull., 35(11), p. 1383. Size. — Male: length, 9.16 to 9.62 mm; greatest body width, 2.73 to 2.82 mm; fe- male: length, 9.29 to 9.94 mm, greatest body width, 3.12 to 3.25 mm. Color. — Fuscous; head, pronotum, thoracic 24 Tulane Studies in Zoology Vol. 8 33 6'S 36, 7'0 rR-«.j 7'5 CR-S_ 1 8'0 . 7 . 85 50 B NT ' 1 Figures 33-36. North to south variation in total lenji'th. 33. Buenoa platycneniis. 34. Buenoa pallens. 35. Buenoa ijallipes. 36. Buenoa craiisi])es. Abbreviations for localities (at left of each bar) : B-NT = Brazil: Nova Tcutonia; Co-V = Colombia: Villavieja; CR-C = Costa Rica: Cartago; CR-S ^ Costa Rica: Sarapiqui; CR-SJ = Costa Rica: San Jose; Cu = Cuba; GC = Grand Cayman; H-T = Honduras: Tela; J = Jamaica; M-C = Mexico: Campeche; M-Mi = Mexico : Michoacan ; M-Mo =Mex- ico: Morelos; M-0 = Mexico: Oaxaca; M-S = Mexico: Sonora; Pa-V ^ Paraguay : Villairica; Pe-A^Peru: Amazonas; Pe-C = Peru: Cajamarca; Pe-SM = Peru: St. Martin; PR = Puerto Rico; SC = St. Croix; ST = St. Thomas; US-F = United States: Florida; US-T = United States: Texas. Numbers at right of each bar indicate the number of specimens studied. venter and limbs testaceous. Scutellum brown to black with apex light. Abdomen black, except for ventral keel and portions of conexivum. Male structural characters. — Outline of head laterally rounded when viewed from above. Greatest width of head about five times the width of vertex. Synthlipsis ap- proximately one-half the width of vertex. Tylus not inflated; rostral prong originating at basal portion of third rostral segment. Fore femur thickened at apex and with a triangular stridulatory area consisting of about thirty-five ridges. Genital claspers normal. Female structural characters. — Head shaped as in males, about five and one-half times width of vertex. Synthlipsis as in males. Pronotum with disc unimpressed. Saitellum large, with median length greater than that of pronotum. Ovipositor normal in shape, with teeth in two rows, and inner one of few large teeth and an outer one of smaller teeth. Geographic distribution. — This species has not been reported for Costa Rica, al- though the recorded geographic distribution suggests its presence. It has been reported for Mexico, Guatemala, and Uruguay. IV. Geographic Variation in Buenoa In his revision of the Genus Buenoa. Truxal (1953) wrote: "...It is interesting to note that in spite of wide ranges, a strik- ing feature in Buenoa is the lack of geo- graphic variation in most specimens studied. There are only three good examples that are obvious. One case is primarily an example of size variation . . .". He points out that for B. linwiocastoris and B. confusa, there is size variation from a large northern form to a small southern form. This type of clinal variation, known as Bergman's rule, was first reported for mammals ( Bergman, 1847). Some other insects have been found to follow this pattern of geographic vari- ation (Hubbell, 1956), but the number of forms studied and their geographic ranges are too small to permit generalizations in this respect. The geographic range studied by Truxal is from Manitoba in Canada to Florida. Although his studies seem to be conclusive there were questions not yet answered: Is this north-to-south variation true for neo- No. 1 De Abate: Backswimmers of Costa Rica 25 1.4 3_a US-F_I 5 Cur I ^ — 1 19 CR-C_1_ 3 37 1 '14 — 1 r- 'l5 'l6 15 1 7 47 H-Ti mri^ i . 4" (— Pn-U ^ ' ?fl J 39 1 2 0 2 2 CR-S r^=ii^i^^^Hcr— I 8 lil 82 40 Figures 37-40. North to south variation in head width. 37. Biienoa platycnemis. 38. Buenoa pallens. 39. Bnenoa pallipes. 40. Buevoa crassipes. Abbreviations same as in figures 33-36. tropical forms.-' Is it also true for measure- ments other than total length? There is also another question that, as far as I know, has not been answered for insects: Is a reversal of this rule expected once the equator is reached? A report (Hesse et al, 1937) on variations of penguins south of the equator, gives weight to this presumption since birds also follow Bergman's rule. To answer these questions, 717 specimens of four species of Buenoa, which are repre- sented in Costa Rica, were selected for study because of their wide geographic dis- tribution. The species are: B. pallens (rang- ing from Oaxaca, Mexico to Celendin, Peru), B. pallipes (from St. Thomas to Villarica, Paraguay ) , B. platycnemis ( from Sonora, Mexico to San Martin, Peru) and, B. cras- sipes (from Heredia, Costa Rica to Nova Teutonia, Brazil). In all specimens, four measurements were taken: total length, head width, vertex width, and width of synthlipsis. These measurements are used in the taxonomy of the group, hence checking their variability was of great interest. The populations studied were grouped according to the states or provinces of origin, except for the island countries where the reduced territorial ex- tension and environmental homogeinity did not justify territorial subdivisions. Total length. — Figures 33-36 show vari- ation in total length for the four species studied. B. platycnemis (fig. 33) has a tendency to diminish in size from north to south, with a clear inversion of this trend once the equator is passed. Except for the populations from Florida and Michoacan, there is no variation to be expected. B. pallens (fig. 34) follows the rule without any deviation, showing also inversion south of the equator. In B. pallipes (fig. 35), there is also a reduction in size from north to south. The inversion south of the equator is not evident in one case: Villarica, Para- guay. The same is also true for B. crassipes (fig. 36), with one population south of the equator not following the expected trend. Head ividth. — For B. platycnemis (fig. 37) the expected comes true, with inversion south of the equator. The few deviations are not significant. B. pallens (fig. 38) and B. pallipes (fig. 39) also follow the expected pattern, showing inversion below the equa- tor. And again, B. crassipes (fig. 40) is the one that, although with a clear north to south variation, does not follow the south of the equator inversion. Vertex width. — B. platycnemis (fig. 41), B. pallens (fig. 42), B. pallipes (fig. 43) and B. crassipes (fig. 44), show reduction in size of head width from north to south. There is only one minor, insignificant, de- viation for B. pallens. The inversion south of the equator is also clear in all cases but B. crassipes. Synthlipsis width. — B. platycnemis (fig. 45 ) has a general trend in diminishing this 26 lulane Studies in Zoology Vol. 8 CR-SJ 42 Pe-C c O'ZO 40 43 o:26 CR-S. 0 S4 0 38 7 Figures 41-44. North to south variation in vertex width. 41. Buenoa platycnemis. 42. Buenoa pallens. 43. Bnevoa pallipes. 44. Buenoa crassipes. Abbreviations same as in figures 33-36. measurement from north to south, but shows deviations for three island popula- tions: Cuba, Grand Cayman, and Puerto Rico. B. pallens (fig. 46) follows the ex- pected variation, except for an island popu- lation (St. Croix;, also showing inversion south of the equator. B. pallipes ( fig. 47 ) and B. crassipes (fig. 48) are clear in their north to south variation, but the latter does not have inversion below the equatorial line. Discussion and conclusions. — Clearly, there is a reduction in measurements from north to south, with inversion once the equator is passed. This geographic clinal variation is due to temperature and therefore could be affected by such other factors as seasonal and altitudinal variations. Compensation for these possibilities is not included in the graphs, but should be borne in mind. For total length, north to south clinal variation is consistent, the exceptions being populations from Florida and Michoacan {B. platycnemis ) . In the first case the sample is too small to be statistically con- clusive. The case of Michoacan, I can ex- plain only as a case of seasonal variation. o'.oe ' olio r 0!l4 ' Ufi-T rJr-i 15 M-Mr r X 1 IQ GCn J^ r-i , 10 PR i^r\ ?7 CR-C 1 3 co-v n^m\ IS p. -A r-^-i 26 43 Pc-SMr^hd. II 1 ] 1 ' 0 10 J 0'I4 ST E 47 Pe-A C Pa-V =1 28 _L. 48 O'lO CR-SJ 0^5 0'20 ^ n A an f4 1 _ Figures 45-48. North to south variation in synthlipsis width. 45. Buenoa platycnemis. 46. Buenoa pallens. 47. Buenoa pallipes. 48. Buenoa crassipes. Abbreviations same as in figures 33-36. No. 1 DeAbate: Backswimmers of Costa Rica 27 The specimens studied were collected dur- ing late summer, which could account for their reduced size in spite of the high lati- tude of Michoacan. Equatorial inversion for total length is also consistent. Two deviations were found to this: the Paraguay sample for B. pallipes and Nova Teutonia, Brazil sample for B. crassipes. In both cases the altitude probably caused the deviations; both localities, in spite of being far south of the equator (26° and 27° latitude) are in lowlands with a climate of tropical type similar to the equa- torial one. For head width and vertex width, the actual results were as expected, with the ex- ception of the samples of B. platycnemis from three island populations. For these populations, the mean values are above the expected. Local variation, preserved and ac- centuated by geographic isolation, is the only answer I can give to explain this devi- ation. Inversion south of the equator is also true except in one case, San Martin, Peru ( B. platycnemis ) . I do not have any data on the altitude of this locality and presume it is in lowlands of equatorial type, which would explain the deviation. More studies on the geographic, altitudi- nal and seasonal variations are desirable. Our knowledge on the evolution of the notonectids is slight and no doubt the com- parative study of populations will be critical in this respect. To date this has not been attempted. V. Acknowledgements I wish to express my appreciation to Dr. George H. Penn, under whose direction this paper was prepared, for his helpful criticism and suggestions. I want to thank also Mr. Pedro L. Vieto, Mr. Leonardo Mata, and Mr. Luis Ferrero who helped to collect specimens, and very special thanks are due to Dr. Salvador Jimenez-Canossa who did a great deal of collecting for me. I am also grateful to Dr. George Byers, Curator of the Snow Entomological Museum at the University of Kansas, and to Mr. Alfonso Jimenez, Curator of the Museo Nacional de Costa Rica, who loaned material. To each of them, I express my deep gratitude. VI. References Cited Bergman 1847. Gottinger Studien. (Cited in : Heese, Richard, W. C. Allee, and Karl P. Schmidt, 1937. Ecological Animal Geography. John Wiley and Sons, Inc., N. Y., xiv + 597 pp.) Calvert, A. C. and P. P. Calvert 1917. A Year of Costa Rican Natural History. Macmillan Co., N. Y., 577 pp. Cazier, Mont A. and Annette L. Bacon 1949. Introduction to quantitative sys- tematics. Bull. Amer. Miis. Nat. Hist., 93(5) : 345-388. Champion, G. C. 1897-1901. Biologia Cen- trali-Ainericana : Insecta Rhynchota. Hemiptera-Heteroptera. Vol. II, xii + 416 pp. Clark, B. and A. H. Hersch 1939. A study of relative growth in Notonecta undidata. Growth, 3: 347-372. Dyar, H. G. 1890. The number of molts in lepidopterous larvae. Psyche, 5: 420-422. Edwards, G. A. 1953. Respiratory mech- anisms. //; .• Roeder, K. D. Insect Physi- ology. John Wiley and Sons, Inc., N. Y. xvi + 110 pp. Hesse, Richard, W. C. Allee, and Karl P. Schmidt 1937. Ecological Animal Geog- raphy. John Wiley and Sons, Inc., N. Y., xvi + 597 pp. HuBBELL, T. H. 1956. Some aspects of geo- graphic variation in insects. Ann. Rev. Ent., 1: 71-88. HuBBS, Carl L. and Clark Hubbs 1953. An improved graphical analysis and com- parison of series of samples. Systematic Zool., 2(2) : 50-56. HuNGERFORD, H. B. 1919a. The biology and ecology of aquatic and semiaquatic He- miptera. Univ. Kansas Sci. Bull., 11: 1-328. 1919b. The male geni- talia as characters of specific value in certain Cryptocerata (Hemiptera-Heter- optera). Ibid., 11: 329-331. 1933. The Genus Noto- necta of the World. Ibid., 21(9) : 5-195. PiCADO, Clodomiro 1913. Les bromeliacees epiphytes considerees comme milieu bio- logique. Bull. Sci. France-Belgique, 47: 215-360. PiTTiER, H. 1942. Capitulos escogidos de la geografia fisica y prehistorica de Costa Rica. Mus. Nac. Costa Rica, Ser. Geogr., 1(1) : 1-56. PiTTiER, H. and P. Biolley 1895. Inverte- brados de Costa Rica. Hemipteros-Heter- opteros. Ann. Inst. Fisico-Geografico Nac. Costa Rica, 6 : 75-83. Rice, Lucille A. 1942. Notes on the bi- ology and species of the three genera of Notonectidae found at Reelfoot Lake, Tennessee. Jour. Tenn. Acad. Sci., 17(1) : 55-67. 1954. Observations on the biology of ten notonectoid species 28 Tulane Studies in Zoology Vol. 8 found in the Doug-las Lake, Michigan, region. Amer. Midi. Nat., 51(1): 105- 132. RosABAL, RiCARDO 1954. Conti'ibucion al estudio de los Phlehotomns de Costa Rica. (Diptera Psychodidae). Pitbl. No. 3, Minisierio Salubridad Piihlica, Iviprenta Nacioval, San Jose, 55 pp. Truxal, Fred S. 1953. A revision of the genus Buenoa (Hemiptera, Notonecti- dae). Univ. Kansas Sci. Bull., 35(11): 1351-1523. Abstract The Notonectidae of the Central Pla- teau of Costa Rica were studied. Six species are reported (Notonecta c. ceres, N. indica, Buenoa ci-assipes, B. pallens, B. pallipes, B. platycnemis) , one of them (N. indica) is a first rec- ord for Costa Rica; five other species {N. confusa, N. ochrotJwe, B. anti- gone, B. gracilis, B. ida) from neigh- boring areas are anticipated. All are included in a key to the Costa Rican species. The life cycle of N. c. ceres is described and illustrated. A taxo- nomic analysis of four populations of N. c. rogersi was made showing that this subspecies intergrades with .V. c. ceres and is here considered synony- mous. Growth rates were studied for eight notonectids, the factor 1.3 being considered as the possible growth rate factor for all the members of the fam- ily. North to south variation was stud- ied in samples of twenty-six popula- tions of four species of Buenoa. Reduc- tion in body measurements was ob- served from north to south (Bergman's rule), and inversion of this trend was found in populations south of the equator. TULANE STUDIES IN ZOOLOGY VOLUME 1, 1953-54 Number Price 1 On a new genus and species of mysid from Louisiana (Crustacea, Malacostraca), by Albert H. Banner, pp. 1-8 (June 1, 1953) . .I$0.25 2 A contribution on the life history of the lizard Scincella laterale (Say), by Richard M. Johnson, pp. 9-27 (July 3, 1953) 75 3 An outline for the study of a reptile life history, by Fred R. Cagle, pp. 29-52 (July 28, 1953) 75 4 A population of Holbrook's salamander, Eurycea longicauda guttolineata (Hol- brook), by Robert E. 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New Orleans, 18, La., USA Please make remittance payable to "Tulane University" i NOV -7 1960 yNiVtKSlTY urn ^(D(E)1L(D(§^ Volume 8, Number 2 October 28, I960 «i THREE ASCOCOTYLE COMPLEX TREMATODES (HETEROPHYIDAE) ENCYSTED IN FISHES FROM LOUISIANA, INCLUDING THE DESCRIPTION OF A NEW GENUS FRANKLIN SOGANDARES-BERNAL and JOHN F. BRIDGMAN, DEPARTMENT OF ZOOLOGY, TVLANE UNIVERSITY NEW ORLEANS, LOUISIANA AGE AND GROWTH OF THE SPOT, LEIOSTOMUS XANTHURUS LAC£P£DE BANGALORE I. SUNDARARAJ, DEPARTMENT OF ZOOLOGY, TULANE UNIVERSITY, NBW ORLEANS, LOUISIANA TULANE UNIVERSITY NEW ORLEANS TULANE STUDIES IN ZOOLOGY is devoted primarily to the zoology of the waters and adjacent land areas of the Gulf of Mexico and the Caribbean Sea. Each number is issued separately and contains an individual study. As volumes are completed, title pages and tables of contents are distributed to institutions exchanging the entire series. Manuscripts submitted for publication are evaluated by the editor and by an editorial com- mittee selected for each paper. Contributors need not be members of the Tulane Univer- sity faculty. Manuscripts should be submitted on good paper, as original typewritten copy, double- spaced, and carefully correaed. Two carbon copies in addition to the original will help expedite editing and assure more rapid publication. An abstract not exceeding three percent of the length of the original article must accom- pany each manuscript submitted. This will be transmitted to Biological Abstracts and any other abstracting journal specified by the writer. Separate numbers or volumes may be purchased by individuals, but subscriptions are not accepted. Authors may obtain copies for personal use at cost. Address all communications concerning manuscripts and editorial matters to the editor; communications concerning exchanges, and orders for individual numbers to the Librarian, Meade Natural History Library. When citing this series authors are requested to use the following abbreviations: Tulane Stud. Zool. Price for this number: $0.65. George Henry Penn, Editor Meade Natural History Library, Tulane University, New Orleans, U. S. A. Associate Editor: Franklin Sogandares-Bernal TULANE STUDIES IN ZOOLOGY Liunnr.i NOV- 7 1960 HARVARD UNIVERSITY Volume 8, Number 2 October 28, I960 CONTENTS THREE ASCOCOTYLE COMPLEX TREMATODES ( HETEROPHYIDAE ) ENCYSTED IN FISHES FROM LOUISIANA, INCLUDING THE DESCRIPTION OF A NEW GENUS Franklin Sogandares-Bernal and John F. Bridgman 31 Editorial Committee: H. W. Manter, Professor of Zoology, University of Nebraska, Lincoln, Nebraska Walter E. Martin, Professor of Biology, University of Southern California, Los Angeles, California Robert B. Short, Professor of Zoology, Florida State University, Tallahassee, Florida AGE AND GROWTH OF THE SPOT, LEIOSTOMUS XANTHURUS LACEPEDE Bangalore I. Sundararaj 41 Editorial Committee: Charles M. Breder, Jr., Curator and Chairman, Department of Fish and Aquatic Biology, American Museum of Natural History, New York, New York Kenneth D. Carlander, Professor of Zoology, Iowa State University, Ames, Iowa Edward C Raney, Professor of Zoology, Cornell University, Ithaca, New York THREE ASCOCOTYLE COMPLEX TREMATODES ( HETEROPHYIDAE) ENCYSTED IN FISHES FROM LOUISIANA, INCLUDING THE DESCRIPTION OF A NEW GENUS ' FRANKLIN SOGANDARES-BERNAL and JOHN F. BRIDGMAN, Department of Zoology, Tulane University New Orleans, Louisiana Results of preliminary investigations of Locality of second intermediate host. — West heterophyid trematodes enq^sted in littoral end of U. S. Highway 11 Causeway, south poeciliid and cyprinodont fishes from brack- shore of Lake Pontchartrain, Louisiana; ish Lake Pontchartrain, Louisiana, are re- new locality record. ported. Infected poeciliids and cyprino- Discussion. — Burton (1956) described this donts form a natural source of infection for species from specimens collected from the wading birds and certain mammals which conus arteriosus of Mollienisia latipinna in feed on them. At times low intensities of Florida. He was able to obtain gravid adults infection in wild adult birds with the Asco- from experimental infections in chicks, but cotyle complex of species, from areas of was unable to observe the flame cell pattern heavily infected poeciliid and cyprinodont which in our specimens is 2[(2 + 2) -\- (2 enzooicity, show that some immunity (age?) _j_2)}. factor may be in operation. Evidence of a Price (1936) sectioned specimens of ^J- presumptive immunity was observed by one cocotyle megalocephala Price, 1932, but did of us (F.S.) on the west coast of Florida, not report a membrane surrounding the Nestling birds believed to be about from rnuscular oral appendage of this species, one to four days old sometimes had a higher Metacercariae of Ascocotyle leighi collected intensity of infection with Ascocotyle com- from the heart of Mollienisia latipinna from plex species than their parents. Exposure Lake Pontchartrain, Louisiana, were exam- of cercariae of the Ascocotyle complex of ined microscopically for details of the mus- species, when these are known, to sera from cular oral appendage. This appendage seems naturally infected nestling and adult birds to be surrounded by a thin, well defined, may produce interesting results. membrane which is continuous with at least The broad spectrum of definitive hosts of the basal portion of the oral sucker. This Ascocotyle complex species, coupled with membrane is not apparent in whole mounts the modern reappearance of uncooked ex- stained with Delafield's hematoxylin and otic dishes, may eventually cause these tre- can best be observed in live material when matodes to be of public health importance the tip of the appendage is contracted, in this country. When the appendage is relaxed, the sur- Acknowledgements are extended to Mr. rounding membrane seems to stretch and C. W. Philpott, and Dr. B. I. Sundararaj, of adhere so closely to the appendage that it our department, for aid in collecting fish is difficult to observe. The overlap of the intermediate hosts muscular oral sucker appendage with the TT I u • r- J II pharynx varies as has been clearly pointed Unless otherwise specified, all measure- ^ { ,, . ,ir,co\ j c i j j .,,. ^ out by Martin (195-)) and Stunkard and ments are in millimeters. ,, ^ ,^ncc\c'n . i i Uzmann (1955) for Parascocotyle lagent- 1. Ascocotyle letght Burton, 1956 ^^^^^^ ^^j Parascocotyle diminuta respec- Second intermediate host m Loumana.— ^-^^ Prolonged observations of Ascoco- Molhemsta lattpmna LeSueur, sail-f in molly ^^^^ /^ -^^ • metacercariae, under slight cover- ( family Poeciludae). ^jjp pressure, revealed that the extension of Location. — In lumen of conus arteriosus and the forebody did not always control the lumen and wall of ventricle of heart. length of the muscular oral appendage. Vari- TZZT. ... . , . ^ ation in position of the appendage is due iThis investigation was supported in part • r u j n by a grant (G-13000) from the National ^^ extension of the appendage as well as Science Foundation. contraction of the forebody which in turn 32 Tulane Studies in Zoology Vol. 8 shortens the distance between the pharynx and oral sucker. The latter factor seems to be the major cause of variation. The ventrogenital sac wall of metacer- cariae of Ascocotyle leighi varies in shape. Live metacercariae were observed, under a floated coverslip, to orient the acetabular concavity anteriorly and to clasp the wall of the ventrogenital sac. Repeated obser- vations revealed that this acetabular sucking action modified the shape of the ventro- genital sac wall. Perhaps acetabular manip- ulations occasionally serve the purpose of ejecting eggs from the ventrogenital sac in gravid worms. The gonotyl of Ascocotyle leighi is as pictured by Burton (1956). The gonotyl fills most of the ventrogenital sac and ap- pears to be provided, when live material is studied under 1,250X magnification, with a patch of very minute spines on its ven- tral surface adjacent to the ventrogenital sac membrane. The gonotylar spines are not visible in specimens stained with Delafield's hematoxylin. 2. Parascocotyle diminuta Stunkard and Haviland, 1924 (Figure 1) Second intermediate hosts in Louisiana. — Cyprinodon rariegatus Lacepede, broad killfish, Fundulus grandis (Baird and Gir- ardj, chub; Fundulus jenkinsi (Evermann), chub; Lucania parva ( Baird and Girard ) , rain water fish (family Cyprinodontidae); and Mollienisia latipinna LeSueur, sailfin molly (family Poeciliidae) ; all new host records. Location. — Gill filaments of all hosts. Locality.. — West end of U. S. Highway 1 1 Causeway, south shore of Lake Pontchar- train, Louisiana; new locality record. Discussion. — P. diminuta reported here ap- pears to be the same species reported by Stunkard and Uzmann (1955). Stunkard and Haviland (1924) named and described Parascocotyle diminuta from rats collected at Clason Point, New York. Tlieir .specimens had lost some of the oral spines. Later Stunkard and Uzmann ( 1955) studied the partial life history of a tre- matodc that they believed to be Parascoco- tyle diminuta. The metacercariae were found in naturally infected Fundulus heteroclitus (Linn.) and Fundulus majalis (Walbaum) collected on the northeastern coast of the United States. Specimens of F. heteroclitus from the P. diminuta type locality were ex- amined by these authors and were found infected with metacercariae that were iden- tified as P. diminuta. Stunkard and Uz- mann (1955) did not mention the estab- lishment of experimental infections of de- finitive hosts with P. diminuta metacer- cariae collected at the type locality. We as- sume that the metacercarial cysts studied by these authors were at least dissected, and oral spination and other morphological de- tails observed. The occurrence of inter- mediate hosts infected with Parascocotyle metacercariae at the type locality lend sup- port to the hypothesis that the species which Stunkard and Uzmann (1955) reported is Parascocotyle diminuta on epizootiological grounds. Hutton and Sogandares (1958) followed the description of Stunkard and Uzmann (1955) when they identified egg- producing adult specimens of P. diminuta obtained from a hamster experimentally ex- posed to metacercariae from the gills of Fundulus similis ( Baird and Girard ) col- lected in the vicinity of St. Petersburg, Florida. On physiological and morphologi- cal bases, the identification of P. diminuta by Hutton and Sogandares (1958) is in accordance with evidence presented by Stunkard and Uzmann (1955). These lat- ter authors were able to obtain gravid adults of P. diminuta from rats and hamsters though not from mice or chicks. Chicks proved to be refractory to infection. Speci- mens of P. diminuta from Mollienisia lati- pinna in Louisiana produced eggs in a mouse but not a hamster. Martin (1953) studied the partial life-history of a trema- tode that he believed was identical with Parascocotyle lageniformis (Chandler, 1941). He collected metacercariae from the gills of Fundulus pallidus Evermann in Texas, and obtained gravid adults from experi- mental infection of chicks. Although Stun- kard and Uzmann ( 1955 ) reported chicks refractory to infection with P. diminuta, they did not state the age or food of the chicks. As is well known new-born chicks are sometimes more susceptible to trematode infections than arc older ones. Furthermore, experimental infections of older ciiicks are sometimes dependent upon diet. Thus, at present we cannot evaluate the physiological No. 2 Sogandares-Bernal and Bridgman: Ascocotyle Complex Trematodes 33 host-specificity of the two species reported by these authors. Chandler (1941) and Martin (1953) could not have known the details of the oral spination of P. diminuta since it was not until 1955 that Stunkard and Uzmann redescribed the species. On morphological grounds there is little doubt that P. diminuta Stunkard and Haviland, 1924, and P. lageniformis (Chandler, 1941) are identical. All meristic and morphologi- cal characters of the two species appear to overlap. The possibility of morphologically identical physiological strains or species pre- cludes a definite stand regarding the synon- ymy at this time. We are in agreement with Martin (1953) that Phagicola nana (Ransom, 1921) of Byrd and Reiber (1942) from a Louisiana muskrat is probably P. lageniformis, and thus is possibly conspe- cific with P, diminuta. Poeciliid and cypri- nodont fishes are frequently found living in the same brackish marshes with musk- rats in the New Orleans area. Another view is that P. diminuta of Stunkard and Uzmann, 1955, is in reality Parascocotyle lageniformis (Chandler, 1941) and that the taxon Parascocotyle diminuta Stunkard and Haviland, 1924, is a different species. This last possibility is cautiously not subscribed to here. This doubt will always remain be- cause the type material of P. diminuta lacks a complete set of oral spines. Stunkard and Uzmann (1955) reported experimental infections of laboratory-raised Larus argentatus (Linn.) and Nycticorax nycticorax (Linn.). These authors did not state whether their Larus specimen was hatched in the laboratory. One of us (F.S.) found a large percentage of several species of coastal birds with estimated ages of one to four days, infected with trematodes due to feeding of infected food material by their mothers. The Nycticorax apparently infected by Stunkard and Uzmann was a young female captured in Bronx Park, New York. Thus, we do not know if Stunkard and Uzmann actually infected their birds experimentally. The fact remains that these hosts were found infected with P. diminuta. Price (1933) reported P. diminuta from Butorides. Hutton and Sogandares (I960) reported P. diminuta from naturally infected Phalacrocorax auritus floridanus (Audubon) and Hydranassa tricolor ruficollis (Gosse) in Florida. To this list we now add Nycti- corax nycticorax hoactli (Gmelin) and Pro- cyon lotor ( Linn. ) from the west coast of Florida. Mr. Larry Ash, Department of Parasitology, Tulane University, has also given us some specimens of P. diminuta collected from a racoon in Louisiana. Thus P. diminuta appears to be a polyxenous para- site known to occur naturally in at least two or possibly three unrelated mammals and five or possibly six birds. P. diminuta populations from different localities may prove to have developed into "strains" which are identifiable only on a physiologi- cal basis. The possibly many faceted phy- siological host-specificity of P. diminuta metacercariae from different intermediate hosts and localities is being investigated further in this laboratory. Metacercariae of P. diminuta collected by us were observed alive under slight cover- slip pressure. Cysts in the gill filaments of Fundulus jenkinsi (fig. 1) were 0.136 to 0.200 long and were oval in shape. Cysts from the gills of Mollienisia latipinna were 0.200 to 0.201 long by 0.119 to 0.144 wide. The surrounding cyst membranes, gonotyl spination, and flame cell pattern (2 [(2 -\- 2) -f- ( 2 + 2 ) } ) are as reported by Stun- kard and Uzmann (1955). Mechanically excysted metacercariae have respectively 16 and 2 oral spines in one complete and an incomplete dorsal accessory row. Metacer- cariae of P, diminuta from different inter- mediate hosts in Louisiana possessed a con- stant number and arrangement of oral spines. 3. Pseudascocotyle mollienisicola, n. gen., n. sp. (Figures 2-4) Second intermediate host in Louisiana. — Mollienisia latipinna LeSueur, sailfin molly (family Poeciliidae). Location. — Encysted on wall and surface of intestine, body musculature, and on gill branchiae. Locality of second intermediate host. — West end of U. S. Highway 1 1 Causeway, south shore of Lake Pontchartrain, Louisiana. Holotype.—U. S. Nat. Mus. Helm. Coll. No. 39446. Diagnosis (measurements on 3 gravid speci- mens, obtained from an experimental ham- ster infection, killed in boiling water). — Body flattened dorsoventrally, pyriform in outline, 0.476 to 0.527 long by 0.221 to 34 Tulane Studies in Zoology Vol. 8 0.255 wide. Forebody 0.255 to 0.289 long, a rudimentary muscular appendage, lacking Cuticle completely spined to level of testes, oral spines; 0.036 to 0.036 wide by 0.056 "Eyespots" present in region of prepharynx to 0.056 from anterior end of sucker to and/or pharynx. Oral sucker terminal, with posterior tip of muscular appendage. Pre- o?^ 8 Figures 1-8. 1. Parascocotyle diminuta; metacercaria encysted in gill filament of Fiindti- lus jenkivsi. 2. Psciidascocotyle mollienisicola, sp. nov., ventral view. 3. Same; terminal genitalia and acetabulum oriented anteriorly along longitudinal axis of body. 4. Same; uterine eggs. 5. Ascocotyle, se7isu stricto; representative oral and cuticular spination. 6. Parascocotyle, sensu stricto; representative oral and cuticular spination. 7. Phagicola, sensu stricto; representative oral and cuticular spination. 8. Pscndascocotyle, sensn stric- to; representative cuticular spination. Unless otherwise specified, all drawings were made with the aid of a camera lucida. The projected scales have the value in millimeters. No. 2 Sogandares-Bernal and Bridgman: Ascocotyle Complex Trematodes 35 pharynx inserting ventral to muscular ap- Small heterophyid trematodes with a dorso- pendage of oral sucker; 0.088 to 0.100 long, ventrally flattened pear-shaped body. "Eye- or about 1.57 to 1.78 times longer than oral spots" present. Cuticle spined. Oral sucker sucker, depending upon contraction of fore- terminal, lacking spines, with a rudimentary body. Pharynx 0.040 to 0.048 long by muscular appendage. Prepharynx, pharynx, 0.040 to 0.040 wide. Esophagus from 0.044 and esophagus present. Ceca 2, one on each to 0.052 long, depending upon contraction side of body, terminating a short distance of forebody. Ceca 2, connecting with esoph- posterior to equator. Acetabulum present, agus, one on each side of body, extending Ventrogenital pore immediately anterior to a short distance posterior to acetabulum. acetabulum, followed by an anteriorly di- Acetabulum 0.048 to 0.048 long by 0.056 rected ventrogenital sac bearing, on its an- to 0.056 wide. Sucker width ratio about terior portion, a prominent gonotyl which is 1:1-4. transversely spined at its equator. Testes 2, Ventrogenital pore median followed by ^^'^^ ^y side, in posterior end of body. Semi- a ventrogenital sac with a gonotyl about "^^ vesicle non-muscular, saccular, extending 0.012 to 0.016 long by 0.044 to 0.048 ^^om a short distance behind acetabulum to wide at its anterior border. Gonotyl with a insert sinistrally on ventrogenital sac at level ventral set of 17 conspicuous spines ar- of posterior border of gonotyl; surrounded ranged equatorially in a transverse row. ^Y prostate cells at junction with ventrogeni- Testes 2, in posterior V4 body, side by side; ^'^^ sac. Ovary between acetabulum and sinistral testis 0.048 to 0.064 long by 0.048 testes, slightly displaced to right of body to 0.072 wide; dextral testis 0.064 to 0.064 midline. Seminal receptacle adjacent and long by 0.056 to 0.076 wide. Seminal vesi- sinistral to ovary. Mehlis' gland amid ovary, cle saccular, extending from a short distance seminal receptacle, and sinistral testis. Ovi- posterior to acetabulum to insert on sinistral duct ciliated (in metacercaria ) . Vitelline side of ventrogenital sac at level of posterior glands composed of coarse follicles, extend- border of gonotyl where it is surrounded by ^^& ^^om behind testes to level of ovary, prostate cells. Ovary between acetabulum overlapping testes dorsally and ventrally on and testes, displaced to right of body mid- ^^^^^ anterior course; vitelline reservoir at line; oval in shape, 0.056 to 0.076 long by ^^^^^ o^ Mehlis' gland. Uterus confined 0.068 to 0.076 wide. Seminal receptacle between pretesticular area and cecal bifurca- equatorial and sinistral to ovary. Mehlis' "O"' approaching ventrogenital sac on its gland amid ovary, seminal receptacle, and dextral side, entering sac anteriorly where sinistral testis. Oviduct ( visible in live '"^ penetrates the gonotyl to open on its metacercariae ) ciliated. Vitelline glands of median posterior border. Eggs small, thin coarse follicles, usually dorsal and ventral to shelled. Excretory vesicle extending from outer aspect of testes, extending from be- terminal excretory pore, intertesticular, usu- hind testes to level of ovary. Vitelline duct ^''y following contour of testes on its an- between testes and ovary, expanding to form terior extent, to end on anterior aspect of a small vitelline receptacle at level of Mehlis' testes; excretory ducts branching in region gland. Uterus in transverse coils, restricted o^ acetabulum; flame cell formula 2[(2 + between testes and cecal bifurcation, ap- 2) + (2 + 2)}. proaching ventrogenital sac on dextral side Type species. — Pseudascocotyle mollienisi- to insert into anterior border where it per- cola. forates the gonotyl to open on its median Discussion. — The genus Pseudascocotyle is jX)sterior border as a uterine pore. Eggs most closely related to the heterophyid gen- (fig. 4) 0.016 to 0.020 long by 0.012 to era Ascocotyle Looss, 1899, Phagtcola Faust, 0.012 wide. Excretory vesicle extending 1920, and Parascocotyle Stunkard and Havi- from a median posterior excretory pore, be- land, 1924, but differs by possessing a tween testes, usually following their contour, gonotyl that is perforated by the uterus, and to end on anterior aspect of testes; excre- by lacking oral spines. Pseudascocotyle seems tory ducts branching at level of or slightly to be most closely related to Phagicola and anterior to acetabulum; flame cell formula Parascocotyle in that the vitellaria extend to 2 [(2 + 2) + (2 + 2)}. the level of the ovary. Generic diagnosis of Pseudascocotyle. — The lack of oral spines in Pseudascocotyle 36 Tulane Studies in Zoology Vol. 8 was at first believed to represent an artifact when adults were removed from an experi- mental hamster infection. Studies of the metacercariae soon removed these doubts. Cuticular spines, which in most species of Ascocotyle, Phagicola, and Parascocotyle be- gin a short distance posterior to the crown spines, leaving a bare zone, extended almost to the oral sucker aperture in our specimens of Pseudascocotyle. We have not made an exact count of sailfin mollies found infected but the incidence is high, at least 95 percent. Sailfin mollies of 23 mm total length were infected. The following artificial key will serve to separate the four genera of the Ascocotyli- nae Yamaguti, 1958, as we presently visual- ize the subfamily. 1. Oral sucker with one or more circlet (s) of spines (figs. 5 to 7) ; vitellaria extending either to level of ovary or to acetabulum 2 Oral sucker lacking spines (fig. 8) ; vitellaria extending to level of ovary — Pseudascocotyle, (this paper) 2. Oral sucker with two complete circlets of spines (fig. 5) ; vitellaria usually extending to level of acetabulum Ascocotyle, seiisii stricto Oral sucker never with two com- plete circlets of spines (figs. 6 to 7) ; vitellaria never ex- tending to acetabulum 3 3. Oral sucker with a single com- plete circlet of spines and an incomplete accessory dorsal row of from 2 to 4 spines (fig. 6) ; vitellaria extending to level of ovary Parascocotyle, sensii stricto Oral sucker with a single com- plete circlet of spines (fig. 7) ; vitellaria extending to level of ovary Phagicola, sensu stricto The ascocotyle Complex The heterophyid trematodes of the gen- era Ascocotyle Looss, 1899, Phagicola Faust, 1920, Parascocotyle Stunkard and Haviland, 1924, and Pseudascocotyle (this paper) are collectively known as the Ascocotyle com- plex. Species of the Ascocotyle complex were placed in the heterophyid sub-families Centrocestinae Looss, 1899, by Price ( 1940) and Ascocotylinae Yamaguti, 1958, by Yam- aguti (1958), though the premetacercarial stages are unknown. The status of the various genera or sub- genera of Ascocotyle complex species has been much disputed by several recent au- thors. At least three different views have developed in connection with generic or sub - generic designation of the species groups. Price (1932, 1936) retained the forms with two complete rows of oral spines in the genus Ascocotyle. He reserved the genus Phagicola for those species with a single and or second dorsal incomplete row of oral spines. This view seemingly re- ceived support from Martin (1951, 1953) and others. Stunkard and Uzmann (1955) reviewed the literature concerning Ascoco- tyle complex species, and maintained that Parascocotyle is a synonym of Phagicola and that the latter is a subgenus of Ascocotyle. Yamaguti (1958) disregarded the number of rows of oral spines and relied upon a character that almost always coincides with oral spination, the anterior vitelline extent, to separate Ascocotyle from Phagicola. Ac- cording to Yamaguti (1958), Parascoco- tyle is a synonym of Phagicola. Burton (1958) recognized Ascocotyle and Phagi- cola. Almost simultaneously with the ap- pearance of Yamaguti's volume I (1958), Hutton and Sogandares (1958) arrived at conclusions somewhat similar to his except for regarding Parascocotyle a valid genus. Hutton and Sogandares (1958, 1959) used the anterior vitelline extent only to separate Ascocotyle from Phagicola and Parascoco- tyle. The use of the anterior vitelline ex- tent was nothing new since Witenberg ( 1929) had used this character to separate Parascocotyle from Ascocotyle. Witenberg considered Phagicola a synonym of Paras- cocotyle. but Price ( 1932 ) clearly pointed out that Phagicola has date priority. From the systematic point of view there appear to be four species groups in the Ascoco- tyle complex. Ascocotyle angeloi Travassos, 1928, possesses intergrading characters (2 complete rows of oral spines and vitellaria to ovary) between Ascocotyle, sensu stricto. ( forms with 2 complete rows of oral spines and vitellaria usually extending to level of acetabulum), Phagicola. sensu stricto, (forms with 1 complete row of oral spines and vitellaria extending to level of ovary), Paras- cocotyle, sensu stricto (forms with one com- No. 2 Sogandares-Bernal and Bridgman: Ascocotyle Complex Trematodes 37 plete row plus one incomplete dorsal acces- sory row of oral spines and vitellaria extend- ing to level of ovary), and Pseudascocotyle (forms lacking oral spines and vitellaria extending to level of ovary). Within a phylogenetic scheme, A. angeloi would tend to reinforce the closeness of relationship be- tween Ascocotyle, Phagicola. Parascocotyle, and Pseudascocotyle. Another view is that Ascocotyle, Phagicola, Parascocotyle, and Pseudascocotyle are sub-genera of Ascoco- tyle. Schiller (1957) X-irradiated eggs of Hy- menolepis nana (Siebold, 1852) to demon- strate that the rostellar hooks of this cestode seem, to be a stable meristic character. Pos- sibly this stability may apply to the oral spines of certain trematodes under normal conditions. Examinations of several hun- dred specimens of certain Ascocotyle com- plex species by one of us ( F.S. ) seems to bear out this point. Wolfgang (1955) did not find a stability of numbers or num- ber of rows in the oral spines of the acan- thocolpid trematode Stephanostomum bac- catuvi ( Nicoll, 1907) from several hosts in Canada. This variation observed by Wolf- gang (1955) possibly may be attributed to a study of worms from abnormal hosts or from superinfections, though he does not make clear the hosts and the intensities of infections from which the abnormal trema- todes were taken. Such great variations in oral sucker spination certainly have not been observed by one of us ( F.S. ) in many specimens of several Stephanostomum spe- cies collected in the tropical American At- lantic and Pacific. Tlie structure of the terminal genitalia of Ascocotyle complex species has not been used as a device to separate species groups. The terminal genitalia have rarely been de- scribed in detail because these structures are difficult to observe even with the best optical equipment. The gonotyl of Ascoco- tyle complex species is variable in spination, shape, and structure. The gonotyl may pos- sess spines or refractile chitin-like bars. These spines or bars are difficult to ob- serve in stained whole mounts, though they are rather easily observed in live specimens. Apparently no spines or bars have been pre- viously reported from the gonotyl of species of Ascocotyle sensu stricto. Metacercariae of Ascocotyle leighi Burton, 1956, from the heart of Mollienisia latipinna Le Sueur in Louisiana, Parascocotyle diminuta Stunkard and Haviland, 1924 from the gills of Fun- dulus sinijlis ( Baird and Girard ) in Florida, Fundulus jenkinsi ( Evermann ) , Fundulus grandis ( Baird and Girard ) , Lucania parva (Baird and Girard), and Cyprinodon varie- gatus, Lacepede in Louisiana, and Phagicola longa (Ransom, 1920) from the pericardial membrane of Mugil cephalus Linn, and Mu- gil curema Cuv. and Val. in Florida, were observed for details of the gonotyl. As pre- viously mentioned, very fine gonotyl spines appeared to be present in the gonotyl of Ascocotyle leighi. Parascocotyle diminuta possess gonotylar spines as reported by Stun- kard and Uzmann (1955). The gonotyl of Phagicola longa possesses chitin-like bars or rodlets. The gonotyl of Pseudascocotyle ( this paper ) has been described above. The gonotyl of Ascocotyle, Phagicola, and Paras- cocotyle is apparently not perforated by the terminal genital ducts, whereas the uterus appears to perforate the gonotyl of Pseudas- cocotyle. Ascocotyle complex species have one de- tail in common; they all possess a character- istic muscular oral sucker appendage that is not found in other heterophyid trema- todes. The flame cell pattern of the meta- cercariae of certain Ascocotyle, Phagicola. Parascocotyle, and Pseudascocotyle, species which we have observed in Florida and Louisiana is 2[(2 + 2) + (2 + 2)]. This flame cell pattern corresponds with that of Centrocestus armatus (Tanabe, 1922) and Centrocestus formosanus (Nishigori, 1924) as reported by Yamaguti (1938) and Mar- tin (1958) respectively. Centrocestus 'Looss, 1899 is the type genus of the Centrocestinae Looss, 1899. Other Centrocestinae with a flame cell pattern of2[(2 + 2) + (2 + 2)] include the genera Pygidiopsis Looss, 1907 and Pygidiopsoides Martin, 1951. Martin (1951) included Caimanicola Freitas and Lent, 1938 and Lacerdaia Travassos, 1931 in the Centrocestinae although Price ( 1940) had previously pointed out that the genus Caimanicola is a synonym of Acanthosto- mum Looss, 1899 (family Acanthostomidae Poche, 1926). One of us (F.S.) agrees with this synonymy, having examined 2 imma- ture specimens of what appears to be the same species collected from the type host. Caiman sclerops Gray, in Pirre River, Darien Tulane Studies in Zoology Vol. 8 Province, Panama. The genus Lacerdaia ap- parently is related to Pygidiopsis and Pygidi- opsoides. though a further study of the ter- minal genitalia of the first would be neces- sary to evaluate this point. We do not agree with Yamaguti (1958) in establishing a new subfamily for Pygidiopsis. and in placing Pygidinpsoides in the Haplorchinae Looss, 1899, and Lcuerdaia in the Opistho- metrinae Yamaguti, 1958. Everything we presently know about these genera seems to indicate that they are closely related. Until further studies prove otherwise, we shall retain the subfamily Centrocestinae for those genera (Centrocestus Looss, 1899, Py- gidiopsis Looss, 1907, Pygidiopsoides Mar- tin, 1951, and Lacerdaia Travassos, 1931) possessing an oral sucker without a muscu- lar appendage and shall tentatively allocate the entire Ascocotyle complex of species to the Ascocotylinae Yamaguti, 1958. The Ascocotylinae are similar to the Centroces- tinae, though differ in details of terminal genitalia and mainly by possessing an oral sucker with a muscular appendage. If a muscular appendage is found on the oral sucker of cercariae of Ascocotyle complex species, it would at present appear to fur- ther strengthen the concept of a separate subfamily for this group of species. The cercariae of Ascocotyle complex species may be of the opthalmopleurolophocercous type with an oral sucker bearing a reduced mus- cular appendage, a non-cellular excretory ves- icle, a flame cell pattern of 2[(2 + 2) + (2 + 2)}, and a number and arrangement of oral spines characteristic of the genus and species represented. Summary 1. The following heterophyid (Ascoco- tylinae Yamaguti, 1958) trematodes are re- ported for the first time from Louisiana: Ascocotyle leighi Burton, 1956; Parascoco- tyle diminuta Stunkard and Haviland, 1924; and Pseudascocotyle mollienisicola ( this pa- per). 2. New second intermediate host records include: Parascocotyle diminuta in Cyprino- don variegatus Lacepede, Fundulus grandis ( Baird and Girard ) , Fundulus jenkinsi { Ev- ermann), Lucania parva (Baird and Girard) (family Cyprinodontidae) ; and Mollienisia latipinna Le Sueur (family Poeciliidae). 3. Additional anatomical details of Asco- cotyle leighi encysted in the type host, Mol- lienisia latipinna Le Sueur from Louisiana, are described. These include the apparent presence of a patch of very minute spines on the ventral aspect of the gonotyl proxi- mal to the ventrogenital sac, and a flame cell pattern of 2[(2 + 2) + (2 + 2)]. 4. A new genus, Pseudascocotyle. is named for the new species P. mollienisicola found encysted in Mollienisia latipinna. Pseudascocotyle differs from other genera in the Ascocotylinae Yamaguti, 1958, by lacking oral spines in both the metacercariae and adults and by possessing a gonotyl per- forated by the uterus. 5. Gravid specimens of Ascocotyle leighi and Pseudascocotyle mollienisicola were ob- tained by feeding metacercariae to a labora- tory-raised hamster. Parascocotyle di?ninuta developed to maturity and produced eggs in an experimentally infected laboratory mouse but not in a hamster. 6. The present status of the Ascocotyle complex of species is discussed and the sub- family Ascocotylinae Yamaguti, 1958 is rec- ognized. We suggest that cercariae of the Ascocotyle complex may be of the opthal- mopleurolophocercous type with a reduced muscular oral appendage, a non-cellular ex- cretory vesicle, a flame cell pattern of 2[(2 -|-2) -|- (2-|-2)] and numbers and row(s) of oral spines corresponding to the species represented. References Cited Burton, P. 1956. Morphology of Ascocotyle leighi n. sp. (Heterophyidae) , an avian trematode with metacercariae restricted to the conus arteriosus of the fish Molli- enesia latipinna Le Sueur. Jour. Parasit., 42: 540-543. 1958. A review of the trematode prenera Ascocotyle (Looss) and Phagicola (Faust) of the family Hetero- phyidae. Proc. Helm. Soc. Wash., 2b: 117- 122. Byrd, E. and R. J. Reiber 1942. Mammali- an trematodes IL Three ilukes from small mammals. Jo^ir. Term. Acad. Sci., 17: 143-148. Chandleui, a. C. 1941. Helminths of musk- rats in southeast Texas. Jour. Parasit., 27: 175-181. HuTTON, Robert F. and F. Sogandares- Bernal 1958. Variation in the number of oral spines of Phagicola lotigicollis Kuntz and Chandler, 1956, and the de- scription of P. ivglei n. sp. (Trematoda: Heterophyidae). Ihid., 44: 627-632. No. 2 Sogandares-Bernal and Bridgman: Ascocotyle Complex Treniatodes 39 1959. Further notes on Trematoda encysted in Florida mullets. Qnart. Jour. Flu. Acad. Sci., 21: 329-334. 1960. Studies en hel- minth parasites from the coast of Flori- da II. Digenetic trematodes fi'om shore birds of the West Coast of P^Iorida. 1. Bull. Mar. Sci. Gulf and Carib., 10: 40-54. Martin, W. E. 1951. Pygkliopsoides spin- dalis n. gen., n. sp. (Heterophyidae:Tre- matcda), and its second intermediate host. Jour. Parasit., 37:297-300. 1953. Redescription of Phagicola lageniformis Chandler (Tre- matoda: Heterophyidae) and ob-erv;- tions on part of its life cycle. Thapar Comm. Volume (India) : 20i-208. 1958. The life histories of some Hawaiian heterophyid trema- todes. Jour. Parasit., 44: 305-323. Price, E. W. 1932. On the genus Phagicola Faust, 1920. Ibid., 19: 166-167. 1933. New host records for trematodes of the genus Phagicola. Ibid., 20: 11. 1936. A new trematode of the genus Ascocotyle (Centrocestinae) . Proc. Helm. Soc. Wash., 3: 31-32. 1940. A review of the trematode superfamily Opisthorchioidea. Ibid., 7: 1-13. Schiller, E. 1957. Investigations on the use of X-irradiation as a mechanism for facilitating the study of morphological variation in Hi/metiolepis nana. Jour. Parasit., 43 (abstract) : 23. Stunkard, H. W. and C. B. Haviland 1924. Trematodes from the rat. Amer. Mus. Novitates., No. 126: 1-10. Stunkard, H. W. and J. R. Uzmann 1955. The killifish, Fiindiihis heteroclitus, sec- ond intermediate host of the trematode, Ascocotyle (Phagicola) diminuta. Biol. Bull., 109: 475-483. Witenberg, G. 1929. Studies on the trema- tode family Heterophyidae. Ann. Trop. Med. Parasit., 23: 131-239. Wolfgang, R. W. 1955. Studies of the tre- matode Stcj)lianostomum baccatani (Ni- coll, 1907) III. Its life cycle. Canad. Jour. Zool., 33: 113-128. Yamaguti, S. 1938. Zur Entwicklungsge- schichte von Centrocestus arrnatus (Tan- abe) mit besonderer Berucksichtigung der Cercarie. Zeitsch. Parasitenk., 10: 2&3-2y6. 1958. Sy sterna Helmin- thwrn. Vol. I. Digenetic Trematodes. Part 1. Interscience Publishers, N. Y., 979 pp. Abstract The trematodes Ascocotyle leighi Burton, 1956; Parascocotyle diminuta Stunkard and Haviland, 1924 and Pseu- doscocotyle molliotisicola n. gen., n. sp., ( Ascocotlyinae: Heterophyidae) were found encysted in poeciliid and cyprino- dont fishes from brackish-water Lake Pontchartrain, Louisiana, All trema- tode species collected represent new lo- cality records. New second intermedi- ate host records include Parascocotyle diminuta in Cyprinodon variegatus La- cepede, Fundulus grandis (Baird and Girard), Fundulus jenkinsi (Ever- mann), Luca)iia parva (Baird and Gir- ard), and Mollienisia latipi)ina Le Sueur. Previously unknown anatomical details are given for Ascocotyle leighi. Metacercariae of all species reported were fed to experimental definitive hosts and mature trematodes were ob- tained. The present status of the As- cocotylinae is discussed. AGE AND GROWTH OF THE SPOT, LEIOSTOMUS XANTHURUS LACEPEDE BANGALORE I. SUNDARARAJ, Department of Zoology, Tulane University, New Orleans, Louisiana Introduction The spot, Leiostomus xanthurus, a com- mon sciaenid fish along the Atlantic and Gulf coasts from Massachusetts to Texas is especially abundant in estuaries and sounds. The commercial fishery is centered in the Chesapeake Bay area and in the CaroUnas. Along the coasts of Louisiana and Texas, the spot is not marketed for human consump- tion to any great extent. Here it is included with trash fish which are used chiefly in making cat and dog food. The object of the present investigation was to determine the age and growth of the spot in the Lake Pontchartrain area, Louisi- ana, based on length-frequency polygons, scale, and otolith studies. Otoliths have not been previously used to determine the age of spot. Previous attempts to determine the age of spot have been based mostly on the in- terpretation of modes in length-frequency polygons. Welsh and Breder (1923) re- ported difficulty in reading its scales. Hil- debrand and Schroeder ( 1928) gave a com- prehensive account of the life history of the Chesapeake Bay spot and stated that the wide range of length of spot taken through- out the year made determination of growth rate difficult. Pearson ( 1928 ) stated that the spawning season for the spot in the Gulf of Mexico extends from late December through March; the peak was reached in January and February. He also reported on the growth and other aspects of the life history. Hildebrand and Cable (1930) de- scribed the larval stages. The smallest spot taken at Beaufort, North Carolina was 1.5 mm in total length; it was assumed to be newly hatched. They also stated that the extended spawning season makes for a great variation in sizes and, as a result, the sizes of fish in successive age groups overlap con- siderably after the second year. Gunter (1938, 1945) reported on the growth and 1 Part of a dissertation submitted in par- tial fulfillment of the requirements for the Ph.D. degree in Zoology at Tulane Uni- versity, April, 1960. other aspects of the life history of the spot in Texas and Louisiana waters. Townsend (1956) and Pacheco (1957) recently showed that age determination based on scale studies is possible in the spot. Dawson (1958) studied the biology and life history of the spot with special reference to South Caro- lina. Materials and Methods In this study 1,418 specimens were used. The collections were made at monthly in- tervals; 354 were collected during July 1953 to May 1954, 145 during January 1955 to September 1955, and 919 during October 1958 to September 1959- The first two series of collections {viz., 1953-54 and 1955) were made in Lake Pontchartrain proper. The 1958-59 collections were obtained from Saw Mill Pass at the Rigolets, lat. 30" 09'N and long. 89° 44'W (fig. 1). Trammel nets, seines, otter trawls, and rotenone were used to collect the specimens. Seine and trawl samples ( Suttkus, Dar- nell, and Darnell, 1954) indicate that young- of-the-year are more abundant in the shal- lower areas of the lake during the period February through April. Later in the season young spot frequent deeper parts of the lake and the trawl is a more effective type of collecting gear. Thirteen trawl stations and seven seine stations were established in Lake Pontchartrain ( fig. 1 ) . The monthly samples from each station were not large enough to allow a critical comparison of growth rate between various stations. Length Measurements. — Length measure- ments were made within a few hours aftr- preservation in 10 percent formalin. Total lengths, measured according to the method of Hubbs and Lagler ( 1947), were used for growth computations throughout this study. For conversion of total length into standard length a ratio of 1:0.816 was computed for specimens from 19 to 49 mm and a ratio of 1:0.773 for specimens from 50 to 270 mm in total length. Scale studies. — Scales used in the deter- mination of age and growth were removed from the left side of each fish below the 42 Tulane Studies m Zoology Vol. 8 LAKE PONTCHARTRAIN Distribution of Monthly Station Locolities o = Trow 1 Station • = Seme Station Figure 1. Map of Li-.ke Pontchartrain showing the distribution of monthly trawl and seine stations. lateral line immediately posterior to the ap- pressed pectoral fin. Regenerated scales were discarded. About 20 scales were re- moved and rubbed between the f.'ngers to clean off epidermis and slime. The scales were then rinsed in water and stored in scale envelopes. The following information was recorded: total length, date of collec- tion, locality, and method of capture. In the laboratory, a few scales were re- moved from each envelope and placed in a 0.5 percent sodium hydroxide solution for a few minutes. Each scale was then cleaned by rubbing between fingers. Impressions of five or six regular scales were made on 3 by 1 inch cellulose acetate strips by use of a roller type press ( mfg. William Dixon Inc., Newark, New Jersey ) . The scale im- pressions were viewed with a Bausch and Lomb microprojector at a magnification of 57.5 X. Scale images were projected verti- cally on a sheet of paper. The positions of the projected annuli were marked on strips cf paper and these were used for back- calculations. All scales with at least one annulus were read several times until the re- sults were concordant. In addition to the enumeration of annuli, the number of circuii from focus to each annulus and to the an- terior margin of the scale were counted. Otolith studies. — A median sagittal inci- sion was made on the head, in a dorso- ventral direction. The two resulting halves were forced outwards and both otoliths re- moved with a forceps. They were stored dry in their respective scale envelopes. Oto- liths were removed only from 1955 and 1958-59 samples. Some authors have emphasized the im- portance of not allowing the otoliths to be- come dry while others stored them dry. Spot otoliths did not lose their clarity after four years of dry storage in this laboratory. Ling ( 1958) stated that the clarity of the sea garfish, Reporbumphiis mclanocheir. oto- liths did not suffer from the effects of No. 2 Sundararaj: Age and Growth of the Spot 43 Figure 2. Scale of spot with one annulus (total length 140 mm, March 27, 1954) drying. However, otoliths of spot preserved in formalin for more than a week were opaque and unusable. Dakin (1939) and Arora (1951) ground otoliths to show the rings clearly. A few spot otoliths ground on a rotary abrasive wheel were compared with their entire coun- terparts and no significant difference was noticed in clarity of the rings. The otoliths were placed in a black bake- lite dish filled with water to a depth of about 4 mm and studied under a stereoscopic binocular microscope using reflected light. The translucent bands appeared opaque by reflected light in contrast to opaque zones which appeared white. The radius of the otolith from the center of the nucleus to the anterior edge and to the various annuli was measured by means of an eyepiece microm- eter. Age and Growth Results of Scale Studies Description of the spot scale. — Pacheco ( 1957 ) gave a brief description of the spot ctenoid scale. Taylor ( 1916) stated that the radii in Cynoscion regalis may afford a supplementary aid in locating annuli, for new radii often originate at an annulus. Pacheco ( 1957) also subscribed to the same view. Examination of the spot scale re- vealed that new radii originated at an an- 44 Tulane Studies in Zoology Vol. 8 Fi{i:ure 3. Scale of spot with two annuli (total length 220 mm, March 31, 1953) nulus (fig. 4), although several exceptions were noted. However, with caution, radii may be used as an additional guide to locate an annulus. New radii usually arise in the antero-lateral field on the outside of the al- ready existing radii. The posterior field of the scale is devoid of circuli and radii ( fiys. 2-4;. Grotvth cessation marks. — The character- istics of the spot annulus were determined after examination of about two hundred spot scales. The best character is "crossing over". This is especially evident at the lat- eral areas of the scale. The circuli in the anterior region of the annulus are broken, incomplete, crooked, or wavy, and stand out prominently from the circuli that precede and succeed them. The annulus is parallel to the general contour of the scale and can be traced around the sculptured part of the scale. Sometimes it can be traced on the unsculptured part of the scale( ^'.c-'.. in the region of the ctenii ). The spot annulus has three characteristics by means of which it can be identified. The so-called crossing over at the lateral areas, the broken or in- terrupted circuli in the anterior field of the scale, and, at times, closely approximated circuli in the anterior field (figs. 2-4). A check was considered an annulus only when it was present in all scales of the selected sample. My observations agree witii Pacheco No. 2 Sundararaj: Age and Growth of the Spot 45 Figure 4. Scale of spot with three annuli (total length 243 mm, May 28, 1954), (1957) who stated that the usual charac- teristic of a spot annulus was closer spacing of circuli associated with broken circuli most evident in the postero-lateral area of the scale. False annuli were often encountered and with some practice they were easily identi- fied. The false annulus is often close to an annulus and is more distinct in the anterior part of the scale than in the lateral areas. Sometimes it is more pronounced than an annulus. Its course cannot be followed all the way around the scale because the false annulus usually merges with the annulus. False annuli may be caused by spawning and or by some adverse environmental con- dition. Period of annulus formation. — Time of annulus formation was determined by meas- uring the marginal increments for all scales collected between October 1958 and Sep- tember 1959. The mean marginal incre- ment was minimum in March, and was max- imum in January (fig. 5), and indicates that the annulus is formed in February and early March. After March the marginal incre- ments increase very rapidly. To verify the abovementioned determina- tion all scales collected in January, February, and March of 1959 were re-examined. No annulus was noticed in scales collected in January 1959- An annulus was present in the majority of the scales collected in the latter part of February. The majority of the 46 Tuhme Studies in Zoology Vol. 8 Table 1. Mean lengths of the anterior scale radiu.s (X 57.5), mean total length, )nean i}nmber of circuli, and mean otolith radius of l,il8 spot. Class Number of Mean Anterior Mean Total Mean Numljer Mean Otolith Range Specimens Scale Radius Length of Circuli Radius in mm (Total length in mm) 20- 29 7 9.6 26.7 7.6 30- 39 9 12.8 33.1 10.1 40- 49 7 22.4 43.1 23.6 1.22 50- 59 20 35.6 55.5 40.6 1.29 60- 69 41 44.9 65.3 48.4 1.42 70- 79 78 55.5 74.3 65.6 1.56 80- 89 90 65.3 84.2 73.6 1.71 90- 99 108 78.4 94.8 87.4 1.85 100-109 182 87.2 104.6 98.0 1.94 110-119 220 98.7 114.2 108.5 2.04 120-129 152 106.4 124.1 114.0 2.16 130-139 97 116.8 133.5 124.0 2.24 140-149 56 125.7 144.5 131.4 2.30 150-159 42 138.4 154.0 138.8 2.50 160-169 46 144.8 164.5 150.0 2.59 170-179 45 152.3 175.0 154.2 2.72 180-189 45 167.0 184.0 163.5 2.85 190-199 29 178.0 194.7 170.0 2.95 200-209 29 183.5 203.2 180.0 3.04 210-219 37 190.6 214.4 184.0 3.24 220-229 37 200.2 223.5 195.5 3.38 230-239 21 210.1 234.5 200.2 3.46 240-249 14 222.5 243.5 206.3 3.63 250-259 5 226.0 252.0 213.0 3.67 260-269 270-279 1 233.0 270.0 236.0 3.74 scales from March samples showed an annu- lus plus a small marginal increment; the re- mainder had an annulus but no marginal increment. Pacheco (1957) stated that an- nuli of spot in Chesapeake Bay are formed in October and November. The disparity in the time of annulus formation is possibly due to differences in latitude. The tempera- ture does not drop appreciably in the Lake Pontchartrain area until November and December ( Suttkus, Darnell, and Darnell, 1954). Age groups. — The young usually first ap- pear in Lake Pontchartrain in January. Pre- Table 2. Average calculated total lengths and iyicrements in length of spot collected fro)n Jiih/ V.I53 to May 195Jf, .fantiary 1955 to September 1955, and October 1958 to September 1959, using scales. Age Groiii) Number of Specimens A vera Re Length at A ("apt lire in mm vera E!l c alculated Le 1 llfJtllS (in mm) f( 2 ,,. i>reviou.s Years of Life 3 0 I II III insi 20!) 110.0 ( 24-197) l(!::.l not 22:!) 21S.7 1 IMI 2t7i ■S.ii.r, (210 270) 1 1 1 in.i ( 00.7- 'il S ( K7.2 -|0.!) (10."..7 18.-..S) lOl.O) 202.0) 20)) .'i 1 l.'iCi.s 21 100.1 (KiS.O 21 7 0) 4.0) 22:'..2 (200.0-248.()) .N'imibcr (if MIS — :!.'17 12S .",S l< iil:iteil II Iillll 14:!.,S 200.1 22'"t.2 AvfTii^re liKTeiiients In mill - 14:!.8 48.7 24.1 A\or.iiif To in Indies tal Lenjitl) ."(.7 7.0 8.8 - Only fisli coiniileting year of life were used in eominitinj? iiii r(iiiciit> No. 2 Sundararaj: Age and Growlb of the Spot Al sumably the eggs were spawned either in December or early January. Thus the bio- logical year and the calendar year appear to coincide closely. The 1958 year class was spawned in late 1957 or early 1958 and formed the first annulus in February-March 1959. Thus a spot in the forementioned group was considered to be young-of-the- year during 1958 and of age group 0 until annulus formation in 1959. Photographs of scales from spot of different ages are pre- sented in Figures 2-4. After all scales were "read" and interpreted the average total length for each age group was deter- mined. The increase in length is greatest during the first year and thereafter the growth rate is a decreasing progression ( Table 2 ) . Determination of the length of the fish at the time of scale formation. — Young fish (17 to 38 mm in total length) collected in February 1954 were used to determine the length of the spot at the time of scale for- mation. The skin was stripped off from head to tail and adherent muscle tissue was removed. It was streched on a slide and a drop or two of alizarin red was placed on it. After one minute the preparation was drained and the excess stain removed by washing in 70 percent alcohol. The skin was then dehydrated and mounted in Can- ada balsam. Scales or scale papillae were not noticed in fish which were 17 mm, 19 mm, and 20 mm in total length. One specimen, 21 mm long ( out of three ) had scales or scale pap- illae. Two circuli were observed on caudal peduncle scales from four fish that were 22 mm in total length. Twenty-two millime- ters total length was considered to be the length of the fish at the time of scale for- mation. This value was used in back-calcu- lation of body lengths. There is a row of scales along the lateral line from the caudal fin to the edge of the operculum of fish 24 mm in total length. A group of scales extends ventrally from the middle of the lateral line system. Scales are absent on either side of the mid-dorsal and mid-ventral line. Scales are present on either side of the mid-ventral line in 26 mm fish but the scales are not imbricate. All scales are fully developed and imbri- cate in 31 mm fish. Hildebrand and Cable (1930) working at Beaufort, North Carolina, reported that the scales were not visible on spot 25 mm OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP Figure 5. Mean monthly marginal inci'ements of the scale of spot. Figures in paren- theses indicate number of specimens. 48 Tulane Studies in Zoology Vol. 8 long but were evident nearly everywhere on fish 30 mm long. Body length and scale length relation- ship.— According to Creaser (1926), Gra- ham (1928), Van Oosten (1929), Hile (1941), and Lagler (1956) scales remain constant in number and retain their identity throughout the life of a fish. Johnston ( 1905) was the first to devise a method of calculating the length of a fish for each year of its life by comparing the widths of the yearly areas of the scale. The relationship of total length to scale length was determined from measurements of 1,418 spot. The individual measurements of both the total length and the anterior scale radius for each of the 1,418 spot were plotted on millimeter graph paper and a linear distri- bution was found. The data were grouped by total lengths into 10 mm groups (Table 1, fig. 6 ) . The averages of these groups and the means of their respective scale radii (X57.5) were then used in computing the linear regression equation (Snedecor, 1957): Y = 0.98693X4- (—18.333). where Y = anterior scale radius in millimeters (X57.5), and X = total length in millimeters. Estimates of annual growth. — Creaser (1926), Rounsefell and Everhart (1953), and Lagler ( 1956) list several formulae for back-calculation of body lengths. One fre- quently used formula is the modified form of Fraser (1916): S' L' = C.F. H (L — C.F.J. S The length of fish at the end of each year of life was computed for all fish with at least one annulus using Eraser's formula. The results are shown in Table 2 and the calculated growth curve based on these data is shown in Figure 7. The greatest annual increment ( 143.8 mm ) was during the first year of life • •• • 220 200 • 180 - Jf» •i/ /• iH • in X 160 - ^ ^ • — ' • ^ w E E 140 - • J vt* • • • z •- J ^•. ;.1 218.7 234.5 98.8 ( 4-174) 147.6 ( 96-199) 190.0 (145-222) 207.1 (175-2:56) 1081 209 90 38 128.9 ( 89-175) 135.3 ( 85-182) 142.2 (110181) 39.4 (18 75) 35.8 (19-64) 20.1 (11.33) Niimljer of Records — — 1418 337 128 38 Average Number of Circuli 132.1 38.3 20.1 No. 2 Sundararaj: Age and Growth of the Spot 53 Figures 9-12. Otoliths of spot; N = nucleus. 9. Without annulus; note the false translu- cent ring around nucleus (total length 141 mm, October 23, 1958). 10. With one trans- lucent annulus (total length 180 mm. May 5, 1955). 11. With two translucent annuli (to- tal length 237 mm, May 5, 1955). 12. With three translucent annuli (total length 250 mm, May 5, 1955). 54 Tulane Studies in Zoology Vol. 8 Table 9. Average calculated fatal lengths and increments in lengtJi of sj)()t collected from .hnniary 1955 to Septonber 1H55 and October 1958 to September 1959, using otoliths. Age Giciiip Number of Specimens Average Calculated Len gths (in mm) for Previous Years of Life 1 2 3 I 11 III 123 21 6 149.2 (109.0-200.0) 170.3 (137.2-198.9) 158.6 (137.0-183.0) 214.7 (199.0-2.38.0) — 204.5 (180.0-239.0) 225.1 (197.4-260.1) Niuiiher of Kfc-oi'ds 150 1.50 27 6 Average Calc Lengths in nlated mm 153.3 212.0 225.1 Average Incr in mm ' ements. loo.o 40.0 20.6 Average Total Length in Inches 6.0 8.3 8.9 Only fish completing year of life were used in computing increments. at the blunter anterior end than at the sides or posterior end. Annuli tend to be zones rather than lines." These criteria also apply to spot otoliths. The annuli, as in the Pacific sardine, are very prominent in the anterior blunt end (figs. 10-12). False annuli were noticed occasionally. They were in the form of translucent bands, but they were always incomplete and hence were easily recognized. Determination of the period of annulus formation. — The incidence of translucent margins was plotted as a percentage of all otoliths examined during each month of the year ( Fairbridge, 1951; Ling; 1958). One thousand and sixty-four spot otoliths col- lected during the periods January 1955 to September 1955, and October 1958 to Sep- tember 1959 were used. The otoliths were read without knowledge of the date of col- lection and were classified as having a trans- lucent or an opaque margin (fig. 13). An- nulus formation began in January and con- uj 20 o 9 o z 0 (40) (89) (208) (103) (172) (56) (87) ± X J. X X X X X X ± ± JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Figure 13. Monthly peicentage incidence oi translucent otolith margins. Figures in pa- rentheses indicate the number of specimens. No. 2 Sundararaj: Age and Groivth of the Spot 55 tinued through February and March. Dur- ing February 85 percent of the otoliths al- ready had the annulus. These data corre- spond with the period of annulus formation determined by scale examination. Age groups. — The writer assumed that the nucleus surrounded by the opaque zone covered the period of life from the time of hatching until the formation of the first annulus. The nucleus represents the initial deposition of calcareous material and is com- parable to the focus of the scale. Hickling (1933), Moore (1947), and Ling (1958) have, however, counted the nucleus also. All workers agree that the translucent band is formed during winter and the opaque band during summer. Hickling (1933) and Ling (1958) count- ed the opaque zones in hake otoliths and in sea garfish otoliths respectively and assigned the age according to the number of these bands. In the sea garfish (Ling, 1958) an annulus is laid down around an opaque nu- cleus after about the first six months of life and the first opaque band is formed at the end of the first year. Hence he counted the opaque zones and assigned the fish to year groups according to the number of these bands. The spot otolith is a little different. The opaque zone surrounding the nucleus represents the growth during the spring, summer, and fall. The annulus is formed around the opaque zone some time in Feb- ruary. The presence of a translucent annu- lus indicates that the fish has passed through one winter and hence is a year old; ages were recorded in the number of winters com- Table 10. Average calculated total lengths atid incre- ments in length of spot collected from January 1955 to September 1955, using otoliths. Table IL Average calculated total lengths and incre- m.ents in length of snot collected from October 1958 to September 1959, tising otoliths. Age Group Number of Specimens Average Calculated Length (in mm) for Previous Years of Life 1 o 3 I II III 61 2 1.33.4 166.8 211.5 Number of Records 63 63 2 — Average Calculated Lengths in mm 134.4 211.5 — Average Increments in mm ® 134.4 44.7 — Age Group Number of Specimens Average Calculated Length (in mm) for Previous Years of Life 1 2 o •J I II III 61 19 6 165.2 176.6 158.6 214.6 204.5 225.1 Number of Records 86 86 25 6 Average Calculated Lengths in mm 167.2 212.0 225.1 Average Increments in mm i* 167.2 39.8 20.6 ^ Only fish completing year of life were used in computing increments. ^ Only fish completing year of life were used in computing increments. pleted. Thus a spot in its first year of life belongs to age group 0 and its otolith has no translucent annulus. A spot in its second year belongs to age group I and its otolith has one translucent annulus. Photographs of otoliths from spot of different ages are presented in Figures 9-12. Body length and otolith radius relation- ship.— Hickling (1933) in the hake, Fair- bridge (1951) in tiger flathead, Grainger (1953) in Arctic char, Scott (1954) in yel- lowtail flounder, and Ling (1958) in sea garfish established a relationship between body length and otolith length. The relationship of total length to otolith radius was determined from measurements of 1,064 spot. The individual measurements of both total length and otolith radius for each of the 1,064 spot were plotted on milli- meter graph paper and a linear relationship was found. The data were grouped by total lengths into 10 mm groups (Table 1 ). The averages of these groups and the means of their respective otolith radii were used in computing the regression equation. Because the distribution was a straight line relation- ship, linear regression was followed (Snede- cor, 1957). The following equation was derived: Y = 0.16438X — 9.4418, where Y T=z Otolith radius in micrometer divisions, and X ^ total length in millimeters. Arbi- trary values were substituted for X in the equation and the values for Y were ob- tained which were used to construct a re- gression line (fig. 14). Extrapolation of the line indicates a fish of no length has an otolith with a radius of almost 0 68 mm. 56 Tulane Studies in Zoology Vol. 8 20 40 60 80 100 120 140 160 180 TOTAL LENGTH IN mm 200 220 240 260 Figure 14. Relationship between total length and otolith radius for 1,064 spot. 120 random statistics plotted. Only Ling ( 1958) reported a similar situation in sea garfish. There appears to be a nonlinear relationship between the radius of the spot otolith and the total length of the spot dur- ing the early larval period. After a certain period of growth the relationship is linear ( fig. 14). No attempt was made to find the length of fish at the time of otolith for- mation. VAtimates of annual growth. — The calai- lation of intermediate lengths from otoliths has seldom been attempted. However, Hick- ling (1933) back-calculated the size of age group 0 hake. Fairbridge (1951) calculated intermediate lengths of New South Wales ti- ger flathead. Grainger (1953), Scott (1954), and Ling (1958), back-calculated the lengths at previous ages from measurements of oto- liths of Arctic char, yellowtail flounder, and sea garfish respectively. All these authors assumed that the growth in fish length is proportional to growth in otolith length. Figure 14 indicates that in spot, growth in fish length is proportional to growtli in otolith radius. The concentric bands in the otoliths have already been shown to be annual in formation The for- mula used for calculating the intermediate lengths was 1 ^ — x v, where 1 V mterme- diate length; L = length of fish at capture; V = total otolith diameter; and, v = dis- tance from center of the nucleus to the an- nulus. The length of the fish at the end of each year of life was computed for all fish with at least one annulus ( Table 9 ) . The greatest increase in length ( 153-3 mm ) took place during the first year of life. During the second and third years of life the increments were 40.0 mm and 20.6 mm respectively. Table 9 represents a composite of 1955 and 1958-59 collections; separate tabulations were computed also (Tables 10 and 11 re- spectively). The increment for the 1955 sample during the first year was 167.2 mm, 39.8 mm during the second and 20.6 mm during the third year. A perusal of Table I 1 indicates that the annual increment dur- ing the first year of life was very small when compared to that in 1955. Possibly this is correlated with the time of spawning, avail- ability of f(X)d, temperature, etc. Obviously No. 2 Sundararaj: Age and Growth of the Spot 57 growth patterns vary considerably in the same area from year to year and in adjoining areas because of the variations and fluctua- tions in ecological conditions. Correlation of Scale and Otolith Readings Walford and Mosher (1943) advanced the method of age determination in Pacific sardines by correlating the age marks on both scales and otoliths. Moore (1947) correlated the age marks on scales and oto- liths of sand flounder, while Arora (1951) did the same in the California sand dab. Parallel age determination by scales and otoliths were made in 1,064 spot. Age de- terminations were made separately for the years 1955 and 1958-59 (figs. 15, 16). An inspection of the figures indicates that the calculated lengths based on scales and those based on otoliths are close and either may be used for age determination. Length-frequency Distributions The total length measurements of the spot in Lake Pontchartrain taken by Suttkus, Darnell, and Darnell (1954) during 1953, 1954, and 1955 were classified into size groups with a class interval of 5 mm. The A^^^ 220 - (25)^-^^^ ^>^(6) 210 - /[/^ £ E 3 200 _ //(29) X g 190 LJ _J - / / ^ 180 o ™ // 170 ™ (86) C // 160 - 1 Aei) 150 - 1 1 .. inn AGE IN YEARS Figure 15. Growth curves of spot showing average calculated lengths from scale and otolith measurements. Dots - calculated lengths based on scales (1955) ; circles= calculated lengths based on otoliths (1955). Figures in parentheses indicate the number of specimens. 210- 200- 190- E E 180 Z X 1- 170 o z UJ _l 160 _l < 1- o 150 140- 130- 120- N YEARS Figure 16. Growth curves of spot showing average calculated lengths from scales and otolith measurements. Dots = calculated lengths based on scales (1958-59) ; circles = calculated lengths based on otoliths (1958- 59). Figures in parentheses indicate the number of specimens. length-frequency distribution of each sample was prepared and the samples were com- bined by months (fig. 17). Age group 0. — Judging from Figure 17 a new group of fish appeared in January 1954 ranging in body length from 15 to 24 mm with a modal peak at 22 mm. The growth of this young-of-the-year group can be fol- lowed easily. In February 1954 the range was from 15 to 39 mm with a modal peak at 27 mm. By March 1954, they had at- tained a modal length of 37 mm with a range from 20 to 74 mm. The modal lengths during April, May, and June were 62, 67, and 92 mm respectively. But in July there are three "peaks", one at 107 mm, a second 58 Tulane Studies in Zoology Vol. 8 >- o z u o 20- 200 zi T r 240 260 80 100 120 140 160 180 TOTAL LENGTH IN mm. Figure 17. Length-frequency histograms of collections of spot made during 1953-54-55. No. 2 Sundararaj: Age and Growth of the Spot 59 at 117 mm, and a third at 127 mm. As the length -frequency distribution is a consolida- tion of all samples taken at the various sta- tions in Lake Pontchartrain, one might rea- sonably expect bimodal and trimodal dis- tributions. These differences may be due to differences in nutrition. By December, the young-of-the-year had attained a modal length of 142 mm with a range from 130 to 150 mm. The distribution is bimodal in January with peaks at 132 mm and 142 mm. By the end of January 1955 the group that was spawned in winter of 1953-54 was approximately one year old {i.e., they had passed through one winter ) . They attained a modal length of 142 mm. The calculated length at the end of first year by means of scales and otoliths is 143.8 mm and 153-3 mm respectively which is reasonable agree- ment. A comparison of the monthly station samples of the young-of-the-year spot was made over a period of five months ( April 1954 through August 1954). The results indicate that there was a difference in the mean total lengths for the spot taken from the various stations. For example. Bayou St. John spot (June — 86.9 mm; August — 98.4 mm ) averaged smaller than those from South Draw (June — 93-0 mm; August — 120.3 mm) and Kenner Towers (June — 92.5 mm; August — 114.9 mm) although collected on or about the same date, with the same kind of gear. The young spot presumably group in the lake after their entry and remain in more or less separate populations throughout spring and summer. Suttkus (1955) reported a consistent dif- ference between the mean lengths for young croakers I Micropogon undulatus) taken from various stations in Lake Pontchartrain. Bay- ou St. John croakers averaged considerably smaller than those from South Draw and Kenner Towers. Data were available for various stations in the lake, but the num- ber of spot collected at these stations was not large enough to warrant a comparison. However, in Lake Pontchartrain, there ap- pear to be great differences in rates of growth. Extrapolation of these results of one study area to another widely separated or adjoining is hazardous. Age group I. — The growth of age group I can be continued beyond January 1955 by following the modes in February, March, April, and May 1955. Age group I had attained a modal length of 172 mm by May 1955 with a range from, 155 to 199 mm. Further growth of age group I can be fol- lowed by tracing the modes from July 1953. There is a mode of 197 mm in July 1953 and by October a modal length of 222 mm was obtained. Age group 11. — The growth of the age group II cannot be identified satisfactorily in the length-frequency distributions be- cause of inadequate samples. Many attempts have been made previous- ly to determine the age of the spot by length-frequency polygons (Welsh and Bre- der, 1923; Hildebrand and Schroeder, 1928; Pearson, 1928; Hildebrand and Cable, 1930; Townsend, 1956; Pacheco, 1957; and Daw- son, 1958). Dawson (1958) summarized the conclusions of various authors. Pearson (1928) stated that the young-of- the-year from the Texas coast reached a total length of 130 mm by the end of October. Age group I had a modal length of 190 mm in April and showed very little growth. By November and December age group I spot migrated from bays to the Gulf of Mexico for spawning and did not return to the bays in the spring in sufficient numbers. A similar migration occurs in Lake Pontchar- train. The age group 0 spot is the most abundant age group in the lake and they move out of the lake into the Gulf of Mexi- co by November and December. Age groups I, II, and III spot also move out of the lake into the Gulf of Mexico by November and December, presumably for spawning. No attempt was made to determine the age of spot at maturity. Catch statistics indicate that no spot were taken during December (Suttkus, Darnell, and Darnell, 1954) and this appears to be a case of complete with- drawal of spot from the lake. Age groups II and III are not well represented in the samples from Lake Pontchartrain. A tag- ging program might yield interesting infor- mation on the movements of spot. Welsh and Breder (1923) assigned a modal length of 140 mm to one year old spot at Fernandina, Florida. Hildebrand and Cable (1930) studied the growth of spot in the first year. The young-of-the-year appeared in December and by the following November they had at- tained a total length of 139.3 mm. 60 Tulane Studies in Zoology Vol. 8 Townsend (1956) stated that at an ap- proximate age of one year the spot in Alli- gator Harbor, Florida, range from 122.8 to 166.8 mm in total length. Dawson ( 1958) reported that most South Carolina spot attain between 148.7 to 168.1 mm in total length in their first year. Spot in their second year of life attained between 213.3 to 226.2 mm in total length. Spot in Lake Pontchartrain attained a modal length of 142 mm at the end of the first year of life; growth of the subsequent age groups is not clear because of insuffi- cient samples. Summary and Conclusions This report presents the results of age and growth studies on the spot, Leiostomus xanthurus Lacepede, from the Lake Pont- chartrain area, Louisiana. A total of 1,418 spot collected by vari- ous methods were used in this investigation. The following conversion ratios were cal- culated. Between 19 and 49 mm in total length a ratio of 1:0.816 for conversion of total length into standard length. Between 50 and 270 mm a ratio of 1:0.773 for con- version of total length into standard length. Age and growth of the spot were de- termined primarily by scales and otoliths but were verified by the length-frequency method. Spot scales are ctenoid and only one an- nulus is formed during February and early March each year. New radii often start at an annulus, but a few exceptions were also observed. Nevertheless, the origin of radii may be used as a supplementary guide for the location of an annulus. Scales made their appearance when the total length of the body was 22 mm. The relationship between total length and scale radius was determined from measure- ments of 1,418 spot. The relationship was linear and can be described by the equation Y = 0.98693X+ (—18.333). Fraser's formula was used to back-calcu- late lengths at previous ages. Spot averaged 143.8 mm at the end of the first year of life, 200.1 mm at the end of second year, and 223.2 mm at the end of third year. The average annual increments were 143.8 mm during the first year, 48.6 mm during the second year, and 24.1 mm during the third year. Increase in length is greatest during the first year and thereafter the growth rate slows down. There was fairly good agree- ment on calculated growth of fish of the same and different age groups in different years' collections. The length attained at the end of first year of 1958-59 year col- lection was smaller when compared to that of previous years' collections. Further work will be necessary to determine the nature of factors responsible for slow and fast growth. Growth of various year classes in dif- ferent calendar years was evaluated. The amount of growth made by fish in a par- ticular year of life varied from year to year. An attempt was made to establish a re- lationship between the number of circuli and the age of the fish. On the average 132.1 circuli are laid down from foais to first annulus, about 38.3 circuli from first to second annulus, and about 20.1 between second and third annuli. The number of circuli may be used to determine the ap- proximate age of spot in fractions of a year. Caution must be exercised in apply- ing this method because the variations in the range are considerable. However, the number of circuli, like the radii, can be used as a supplementary guide to locate an annulus. The longest specimen was 270 mm in total length, had attained the age of three, and was in its fourth year of life. The vast majority of the spot probably die or migrate after attaining an age of two years. This is evidenced by the fewer number of spot in age group III. Each otolith has a centrally located nu- cleus surrounded by alternating bands of opaque and translucent areas. The growth marks are clearly visible on the concave side of the otolith. The annulus which repre- sents winter growth appears as a translucent band and the region in between two annuli which represents summer growth appears opaque in reflected light. Only one annulus is formed each year during late January and February. The relationship between total length and otolith radius was determined from measure- ments of 1,064 spot. The relationship was linear and can be described by the equation: Y = 0.16438X — 9.4418. The calculation of intermediate lengths was accomplished by using the direct pro- portion equation. Spot averaged 153.3 mm No. 2 Sundararaj: Age and Growth of the Spot 61 at the end of their first year of life, 212 mm at the end of their second, and 225.1 mm at the end of their third. There was general agreement between the scale year marks and otolith year rings from the same fish. Parallel age determinations by scales and otoliths were made for 1,064 spot. The calculated lengths based on scales and those based on otoliths coincide closely, thereby indicating that either may be used for age determination in the spot. The length-frequency distributions of the spot show the growth of the young-of-the- year very well. They attain a length of 142 mm by January. This closely corresponds with the calculated lengths based on scales and otoliths. Comparison of the monthly station samples of the young-of-the-year spot showed that there was a difference in mean total lengths for spot taken from various stations. Apparently, young spot group in the lake after their entry and remain more- or-less as discrete populations through spring and summer. Growth of age group I can also be traced, though incompletely, in the length-frequency distributions. Growth of age group II cannot be identified satisfac- torily because of insufficient samples. Acknowledgements I am indebted to Dr. Royal D. Suttkus, Tulane University, for suggesting the prob- lem, for his interest, guidance, and use of his extensive data on the spot. The 1953-54 and 1955 material was col- lected by Dr. Royal D. Suttkus during a Biological Study of Lake Pontchartrain, a cooperative investigation of Tulane Univer- sity and the Commercial Seafoods Division ( Mr. Robert Lee Eddy, Jr., Chief ) , Louisiana Wildlife and Fisheries Commission and was placed unreservedly at my disposal. I take pleasure in expressing my apprecia- tion to Mr. Percy Viosca, Jr., Mr. Benny Peterson, and Mr. Miles Parureau, Louisiana Wildlife and Fisheries Commission; Mr. Arnold E. Gussin, Mr. Douglas M. Land- wehr, and Miss Myrna C. Andersson, De- partment of Zoology, Tulane University, for helping me in various ways in the collection of specimens. References Cited Arora, Harbans L. 1951. An investigation of the California sand dab, Citharichthys sordidns (Girard). Calif. Fish and Game, 37: 3-42. Creaser, Charles W. 1926. The structure and growth of the scales of fishes in relation to the interpretation of their life-history, with special reference to the sunfish Eupomotis gihhosus. Misc. Publ., Univ. Mich. Mus., ZooL, No. 17, 1-82. Cunningham, J. T. 1905. Zones of growth in the skeletal structures of Gadidae and Pleuronectidae. Rep. Fish. Bd. Scotland, 23rd Aim. Rept. (1904) pt. 3: 125-140. Dakin, W. J. 1939. The age detei-mination of the tiger flathead, Neoplatycephalus (Colefaxia) macrodon (Ogilby) by means of otoliths. Rec. Austral. Mus., 20: 282- 292. Dawson, C. E. 1958. A study of the biology and life history of the spot, Leiostomus xanthurus Lacepede with special refer- ence to South Carolina. Contrib. Bears Bluff Lab., No. 28, 1-48. Fairbridge, W. S. 1951. The New South Wales tiger flathead (Neoplatycephalus) macrodon (Ogilby). I. Biology and age determination. Aust. Jour. Mar. & Fresh- water Res., 2: 117-178. Fraser, C. McL. 1916. Growth of spring salmon. Trans. Pacific Fish. Soc, 2 (1915) : 29-39. Graham, Michael 1928. Studies of age- determination in fish. Part I. A study of the growth-rate of codling (Gadus cal- larias L. ) on the inner herring-trawling ground. Fish. Invest. Lorid., Series II, 11: 3-50. Grainger, E. H. 1953. On the age, growth, migration, reproductive potential and feeding habits of the Arctic char (Sal- velinus alpinus) of Frobisher Bay, Baffin Island. Jour. Fish. Res. Bd. Canada, 10: 323-370. Gunter, Gordon 1938. Seasonal variations in the abundance of certain estuarine and marine fishes in Louisiana, with particu- lar reference to life histories. Ecol. Mono- gr., 8: 313-346. 1945. Studies on marine fishes of Texas. Publ. Inst. Mar. Sci. (Univ. of Te.vas), 1: 9-190. HiCKLiNG, C. F. 1931. The structure of the otolith of the hake. Quart. Jour. Micros. Sci., 74: 547-561. 1933. The natural his- tory of the hake. IV. Age determination and growth rate. Fish. Invest. Land., Series II, 13: 3-120. HiLDEBRAND, SAMUEL F. and LOUELLA E. Cable 1930. Development and life his- tory of fourteen teleostean fishes at Beau- fort, N. C. Bull. U. S. Bur. Fish., 46: 383-488. and William C. Schroe- DER 1928. Fishes of Chesapeake Bay. Bull. U. S. Bur. Fish., 43: 1-366. HiLE, Ralph 1941. Age and growth of the rock bass, Ambloplites rupestris (Rafi- nesque) in Nebish Lake, Wisconsin. Gl Tulane Studies in Zoology Vol. 8 Trans. Wise. Acad. Sci. Arts & Lett., 33: 189-337. HuBBS, Carl L. and Karl F. Lagler 1947. Fishes of the Great Lakes Region. Bull. Cranbrook Inst. Sci., 26: 1-186. Johnston, H. W. 1905. Scales of the Tay salmon as indicative of ag-e, growth, and spawning habit. Fishery Bd. Scotland, Ann. Rept. No. 23, pt. II: 63-79. Lagler, Karl F. 1956. Freshwater Fishery Biology. Wm. C. Brown Co., Dubuque, Iowa. Ling, J. K. 1958. The sea garfish, Repor- hampus melanocheir (Cuvier and Valen- ciennes) (Hemiramphidae) , in south Aus- tralia : breeding, age determination, and growth rate. Austral. .Jour. Mar. F^resh- water Res., 9: 60-110. Molander, a. R. 1947. Observations on the growth of the plaice and on the forma- tion of annual rings in the otolith. Sven- ska Hydrogr.-Biol. Komm. Skr., 2: 1-9. Moore, Emmeline 1947. Studies on the marine resources of Southern New Eng- land VI. The sand flounder, Lophopsetta aquosa (Mitchill) : A general study of the species with special emphasis on age determination by means of scale and oto- lith. Bull. Bingham Oceanogr. Coll., 11: 1-79. Pacheco, Anthony L. 1957. The length and age composition of spot, Leiostomus xanthurus in the pound net fishery of lower Chesapeake Bay. (Unpublished M.S. thesis, College of William and Mary, 34 pp.) Pearson, John C. 1928. Natural history and conservation of redfish and other commercial sciaenids on the Texas coast. Bull. U. S. Bur. Fish., 44: 129-214. RouNSEFELL, George A. and W. Harry Ev- ERHART 1953. Fishery Science: Its Meth- ods and Applications. John Wiley and Sons, New York. Scott, D. M. 1954. A comparative study of the yellowtail flounder from three Atlan- tic fishing areas. .Jour. Fish. Res. Bd. Canada, 11: 171-197. Snedecor, George W. 1957. Statistical Methods. The Iowa State College Pi-ess, Ames, Iowa. SuTTKUS, Royal D. 1955. Seasonal move- ments and growth of the Atlantic croaker (Micropogon undulatus) along the east Ijouisiana coast. Proc. Gulf and Carih. Fish. Inst., 7th Ann. Session: 151-1.58. , Rezneat M. Darnell, and Jeanne H. Darnell [1954]. Biologi- cal study of Lake Pontchartrain. Ann. Rept. July 1, 1953 to June 30, 1954. Zoology Department, Tulane University. pp. 1-59 (multilithed). Taylor, Harden F. 1916. The structure and grovvdh of the scales of the sque- teague and the pigfish as indicative of life history. Bull. U. S. Bur. Fish. (1914), 34: 287-330. Tovi^NSEND, B. C. Jr. 1956. A study of the spot, Leiostomus xa)ithurus Lacepede in Alligator Harbor, Florida. (Unpublished M.S. thesis, Florida State Univ. 43 pp.) Van Oosten, John 1929. Life history of the lake herring (Leucichthys artedi Le Sueur) of Lake Huron as revealed by its scales with a critique of the scale method. Bull. U. S. Bur. Fish., 44: 265- 428. Walford, Lionel A. and Kenneth H. Mo- SHER 1943. Studies on the Pacific pil- chard or sardine (Sa)-dinops caerulea) 2. Determination of the age of juveniles by scales and otoliths. U. S. Fish and Wildl. Ser., Spec. Sci. Rep., No. 15, 31-95. (re- issued May 1950). Welsh, William W. and Charles M. Bre- DER Jr. 1923. Contributions to life his- tories of Sciaenidae of the eastern United States coast. Bnll. U. S. Bur. Fish., 39: 141-201. Abstract Age and growth of the spot, Leiosto- mus xanthuriis Lacepede, from Lake Pontchartrain area, Louisiana, were de- termined by the scale and otolith meth- ods and verified by length-frequency method. For the study 1,418 spot ob- tained by various methods in 1953-54, 1955, and 1958-59 were used. Annuli on scales and otoliths were formed dur- ing February and early March. The maximum annual increase in length oc- curred during the first year. There- after, the growth rate decreased. An attempt was made to establish a rela- tionship between the number of circuli and the age of spot. The longest speci- men was 270 mm in total length and had attained the age of three and was in its fourth year of life. There was good agi'eement between scale year marks and otolith year rings from the same fish. The calculated lengths based on scales and those based on oto- liths coincide closely, thereby indicat- ing that either may be used for age determination in the spot. The length- frequency distributions of the spot show the growth of the young-of-the-year very well. Young spot taken at vari- ous stations in the lake exhibited dif- ferences in the growth rate. Presuma- bly, young spot group in the lake after their entry and remain as more or less discrete populations through spring and summer. Growth of age group I could be traced, though incompletely, whereas growth of age group II could not be traced in the length-frequency distributions because of inadequate samples. TULANE STUDIES IN ZOOLOGY VOLUME 1, 1953-54 Number Price 1 On a new genus and species of mysid from Louisiana (Crustacea, Malacostraca). by Albert H. Banner, pp. 1-8 (June 1, 1953) . .$0.25 2 A contribution on the life history of the lizard Seincella laterale (Say), by Richard M. Johnson, pp. 9-27 (July 3, 1953) 75 3 An outline for the study of a reptile life history, by Fred R. Cagle, pp. 29-52 (July 28, 1953) 75 4 A population of Holbrook's salamander, Eurycea longicauda guttoUneata (Hol- brook), by Robert E. Gordon, pp. 53-60 (August 15, 1953) 25 5 A redescription of the crawfish Procam- iarus hinei (Ortmann) (Decapoda, Astaci- dae), by George Henry Penn, pp. 61-68 (September 1, 1953) 25 6 A new burrowing crawfish of the genus Procatnbarus from Louisiana and Missis- sippi (Decapoda, Astacidae), by George Henry Penn, pp. 69-76 (September 15, 1953) 25 7 The life history of the crawfish Orconectes (Faxonella) clypeatus (Hay) (Decapoda, Astacidae), by Elsie Wayne Smith, pp. 77- 96 (October 23, 1953) 50 8 Oatrincola gracilis C. B. Wilson, a parasite of marine pelecypods in Louisiana (Cope- poda, Cyclopoida), by Arthur G. Humes, pp. 97-107 (December 21, 1953) 25 9 Hybrid Inviabillty between Rana pipiens from Wisconsin and Mexico, by B. Peter Volpe, pp. 109-123 (February 8, 1954) 35 10 The butterflies and skippers of Louisiana, by Edward Nelson Lambremont, pp. 125- 164 (April 30, 1954) 60 11 Two new species of the genus Oraptemys, by Fred R. Cagle, pp. 165-186 (August 26, 1954) 75 12 The taxonomic status of the mid-Gulf Coast Amphiuma, by Imogene R. Hill, pp. 189-215 (August 26, 1954) 35 Complete volume, including title page and table of contents, (unbound) $4.25 VOLUME 2, 1954-55 1 1 A new Eulimnadia from the rice fields of Arkansas with a key to the American species of the genus (Conchostraca, Lim- nadiidae), by N. T. Mattox, pp. 1-10 (Sep- tember 14, 1954) $0.25 2 Studies In the ecology of the narrow- mouthed toad, Microhyla carolitienaia caro- linenaia, by Paul K. Anderson, pp. 13-46 (November 8, 1954) 50 S A new species of Diaptomus from Louisi- ana and Texas with notes on the subgenus Leptodiaptomua (Copepoda, Calanoida), by Mildred Stratton Wilson, pp. 47-60 (No- vember 29, 1954) 25 4 Three new species and new records of southern miliipeds. by Nell B. Causey, pp. 61-68 (December 28, 1954) 25 5 Notropia iaileyi, a new cyprlnid fish from Pascagoula and Mobile Bay drainages of Mississippi and Alabama, by Royal D. Suttkus and Edward C. Raney, pp. 69-86 (January 12. 1955) 30 VOLUME 2, 1954-55-Continued Number Price 6 A reconsideration of the racer, Coluber constrictor, in eastern United States, by Walter Auffenberg, pp. 87-155 (February 25, 1955) 1.00 7 Notropis Jtypsilepis, a new cyprinld fish from the Apalachicola River system of Georgia and Alabama, by Royal D. Suttkus and Edward C. Raney, pp. 157-170 (Feb- ruary 25, 1955) 30 8 The fishes of two Gulf Coastal marsh areas of Florida, by John D. Kilby, pp. 171-247 (May 4, 1955) 1.00 Complete volume, Including title page, table of contents and index (unbound) ... .$3.75 VOLUME 3, 1955-56 1 Notropis asperifrons, a new cyprinld fish from the Mobile Bay drainage of Alabama and (Georgia, with studies of related spe- cies, by Royal D. Suttkus and Edward C. Raney, pp. 1-33 (July 8, 1955) )$0.50 2 A new Louisiana copepod related to Diap- tomus (Aglaodiaptomua) clavipes Schacht (Copepoda, Calanoida), by Mildred Strat- ton Wilson, pp. 35-47 (August 1, 1955) ... .30 3 A new species of Sternotherua with a dis- cussion of the Sternotherua carinatua com- plex (Chelonia, Kinosternidae), by Don- ald W. Tinkle and Robert G. Webb, pp. 51-67 (August 30, 1955) 50 4 A new Cambarua of the Diogenea section from North Louisiana (Decapoda, Astaci- dae), by George Henry Penn, pp. 71-81 (September 30, 1955) 25 5 Notropia euryzonus, a new cyprinld fish from the Chattahoochee River system of Georgia and Alabama, by Royal D, Suttkus, pp. 83-100 (December 28, 1955) 50 6 Factors influencing the rate of oxygen con- sumption of the dwarf crawfish, Camba- rellua ahufeldtii (Decapoda Astacidae), by Milton Fingerman, pp. 101-116 (December J8, 1955) 35 7 Identification and geographical variation of the cyprinodont fishes Fundulua oliva- ceua (Storer) and Fundulua notatua (Rafl- nesque), by Jerram L. Brown, pp. 117-134, (February 3, 1956) 50 8 The physiology of the melanophores of the Isopod Idothea exotica, by Milton Finger- man, pp. 137-148 (April 12, 1956) 30 9 Osmotic behavior and bleeding of the oyster Craaaoatrea virginica, by Milton Fin- german and Laurence D. Fairbanks, pp. 149-168 (April 12, 1956) 50 10 Anatomy of the eyestalk of the white shrimp, Penaeus setiferua (Linn. 1758), by Joseph H. Young, pp. 169-190 (June 22, 1956) 50 Complete volume. Including title page, ta- ble of contents and index (unbound) $4.00 VOLUME 4, 1956 1 A study of the distribution and taxonomy of the percid fish Percina nigrofaaciata (Agassiz), by Ronald W. Crawford, pp. 1- 55 (August 1, 1956) $0.76 TULANE STUDIES IN ZOOLOGY VOLUME 4, 1956-Continued Number Price 2 Experimental Fi hybrids between Bufo valliceps and Bufo fowleri, by E. Peter Volpe, pp. 59-75 (September 30, 1936) 40 3 An outiine for the study of an amphibian life history, by Fred R. Cagie, pp. 77-110 (October 31, 1956) 40 4 Notes on habitats, systematic characters and life histories of Texas salt water Cyp- rinodontes, by Don G. Simpson and Gordon Gunter, pp. 113-134 (December 31, 1956) .35 5 Dominance-subordinance relationships in the crawfish Camtarellus ahujeldtii, by Mildred Eileen Lowe, pp. 137-170 (Decem- ber 31, 1956) 45 6 Propogation of the white shrimp, Penaeua eetijerus (Linn.) in captivity, by Malcolm C. Johnson and J. R. Fielding, pp. 173-190 (December 31, 1956) 30 Complete volume, including title page, ta- ble of contents and index (unbound) $2.50 VOLUME 5, 1957 1 Oambusia heterochir, a new poeciliid fish from Texas, with an account of its hybrid- ization with O. affinia, by Clark Hubbs, pp. 1-16 (March 18, 1957) *0.30 2 New calanoid copepods of Pontella Dana and Labidocera Lubbock with notes on the distribution of the genera in the Gulf of Mexico, by Abraham Fleminger, pp. 17-34 (March 18, 1957) 30 3 Three new crayfishes from Alabama and Mississippi (Decapoda: Astacidae), by Uorton H. Hobbs, Jr. and Margaret Wal- ton, pp. 37 52 (March 18, 1957) 30 4 Heat death and associated weight loss of the oyster Crasaostrea virginica, by Milton Flngerman and Laurence D. Fairbanks, pp. 53-62 (April 1, 1957) 30 5 The Odonata of Louisiana, by George H. Bick, pp. 69-135 (May 15, 1957) 1.00 6 Endocrine control of the red and white chromatophores of the dwarf crawfish, Cambarellua ahujeldti, by Milton Finger- man, pp. 137-148 (June 7, 1957) 30 7 Hormones controlling the chromatophores of the dwarf crawfish, Cambarellua ahu- jeldti : their secretion, stability, and sepa- ration by filter paper electrophoresis, by Milton Flngerman and Mildred E. Lowe, pp. 149-171 (June 7, 1957) 40 8 Cyprlnid fishes of the subgenus Cyprinella of Notropia. III. Variation and subspecies of Notropia venuatua (Girard), by Robert H. Gibbs, Jr. pp. 173-203 (August 7, 1957) .50 9 The early development of Rana capito aevo- aa, by E, Peter Volpe, pp. 205-225 (Septem- ber 12, 1957) 35 11 The skeleton shrimps (Crustacea: Caprel- lldae) of the Gulf of Mexico, by Joan E. Steinberg and Ellsworth C. Dougherty, pp. 265-288 (December 30, 1957) 40 10 Variation and subspecies of the crawfish Orconectea palmeri (Faxon) ( Decapoda, Astacidae), by George Henry Penn, pp. 229-262 (September 12, 1957) 60 VOLUME 5, 1957-Continued Number Price 12 The systematic status of the suckers of the genus Moxoatoma from Texas, New Mexico, and Mexico, by C. Richard Robins and Edward C. Raney, pp. 289-318 (Decem- ber 30, 1957) 45 Complete volume, including title page, ta- ble of contents and index (unbound) ....$5.00 VOLUME 6, 1958 1 The systematics and ecology of the Sterno- thaerua carinatua complex (Testudinata, Chelydrldae), by Donald W. Tinkle, pp. 1-56 (March 31, 1958) $1.26 2 The butterflies of Mississippi, by Bryant Mather and Katharine Mather, pp. 61-109 (June 6, 1958) 1.00 3 Aquatic and semlaquatlc Hemiptera of Mis- sissippi, by Clifton A. Wilson, pp. 113-170 (September 5, 1958) 1.00 4 The copepod genus Halicyclopa in North America, with description of a new species from Lake I'ontchartrain, Louisiana, and the Texas coast, by Mildred Stratton Wil- son, pp. 176-189 (December 31, 1958). Ontogeny of the first and second pleopods of the male crawfish Orconectea clypeatua (Hay) (Decapoda, Astacidae), by Joe B. Black, pp. 190-203 (December 31, 1958) ... .60 Complete volume, including title page, table of contents and index (unbound) $3.50 VOLUME 7, 1959 1 An illustrated key to the crawfishes of Louisiana with a summary of their distri- bution within the State (Decapoda, Asta- cidae), by George Henry Penn, pp. 3-20 (April 23, 1959). Comparison of the chromatophorotropins of two crayfishes with special reference to electrophoretic behavior, by Milton Flnger- man, pp. 21-30 (April 23, 1959) $0.60 2 A review of the seabasses of the genus Centropristea (Serranidae), by Rudolph J. Miller, pp. 33-68 (July 9, 1959) 0.76 3 Digenetic trematodes of marine fishes from the Gulf of Panama and Bimini, British West Indies, by Franklin Sogandares-Ber- nal, pp. 69-117 (August 24, 1959) 1.00 4 Parasites of the commercial shrimps, Pen- aeua aztecua Ives, P. duorarum Burkenroad, and P. aetijerua (Linnaeus), by Dwayne Nathaniel Kruse, pp. 123-144 (October 19, 1959). The larva of the oak toad, Bufo quercicua Holbrook, by E. Peter Volpe and James L. Dobie, pp. 145-152 (October 19, 1959) 60 Complete volume, including title page, table of contents and index (unbound). ... $2.65 Orders should be addressed to Meade Natural History Library, c/o Department of Zoology, l| Tulane University, New Orleans, 18, La., USA Please make remittance payable to "Tulane University' UBRARY DEC 13 1960 (ttRVARD WmERStlY Volume 8, Number 3 December 2, I960 THE BREEDING HABITS OF THE MOLE SALAMANDER, AMBYSTOMA TALPOIDEUM (HOLBROOK), IN SOUTHEASTERN LOUISIANA C. ROBERT SHOOP, DEPARTMENT OF ZOOLOGY, TULANE UNIVERSITY NEW ORLEANS, LOUISIANA SALINITY RELATIONS OF SOME FISHES IN THE ARANSAS RIVER, TEXAS WILLIAM C. RENFRO, U. S. BUREAU OF COMMERCIAL FISHERIES, BIOLOGICAL LABORATORY, GALVESTON, TEXAS TULANE UNIVERSITY NEW ORLEANS TULANE STUDIES IN ZOOLOGY is devoted primarily to the zoology of the waters and adjacent land areas of the Gulf of Mexico and the Caribbean Sea. Each number is issued separately and contains an individual monographic study, or several minor studies. As volumes are completed, title pages and tables of contents are distributed to institutions ex- changing the entire series. Manuscripts submitted for publication are evaluated by the editor or associate editor and by an editorial committee selected for each paper. Contributors need not be mem- bers of the Tulane University faculty. Manuscripts should be submitted on good paper, as original typewritten copy, double- spaced, and carefully corrected. Two carbon copies in addition to the original will help expedite editing and assure more rapid publication. An abstract not exceeding three percent of the length of the original article must accom- pany each manuscript submitted. This will be transmitted to Biological Abstracts and any other abstraaing journal specified by the writer. Separate numbers or volumes may be purchased by individuals, but subscriptions are not accepted. Authors may obtain copies for personal use at cost Address all communications concerning manuscripts and editorial matters to the editor; communications concerning exchanges, and orders for individual numbers to the Librarian, Meade Natural History Library. When citing this series authors are requested to use the following abbreviations: Tulane Stud. Zool. Price for this number: $0.50. George Henry Penn, Editor Meade Natural History Library, Tulane University, New Orleans, U. S. A. Associate Editor: Franklin Sogandares-Bernal TULANE STUDIES IN ZOOLOGY ' imm D£C 1 3 I960 HARVARD I UNfl/fRSITY ' Volume 8, Number 3 December 2, I960 CONTENTS THE BREEDING HABITS OF THE MOLE SALAMANDER, AMBYSTOMA lALPOIDEUM (HOLBROOK), IN SOUTHEASTERN LOUISIANA C Robert Shoop 65 Editorial Committee: Harold A. Dundee, Assistant Professor of Zoology, Tulane University, New Orleans, Louisiana Robert F. Inger, Herpetological Editor, Chicago Natural History Museum, Chicago, Illinois Philip W. Smith, Associate Taxonomist, Illinois Natural History Survey, Urbana, Illinois SALINITY RELATIONS OF SOME FISHES IN THE ARANSAS RIVER, TEXAS William C. Renfro 83 Editorial Committee: Franklin C. Daiber, Associate Professor of Biology, University of Delaware, New- ark, Delaware Earl E. Deubler, Jr., Associate Professor of Zoology, Institute of Fisheries Research, University of North Carolina, Morehead City, North Carolina George K. Reid. Professor of Biology, Florida Presbyterian College, St. Petersburg, Florida THE BREEDING HABITS OF THE MOLE SALAMANDER. AMBYSTOMA TALPOIDEUM (HOLBROOK), IN SOUTHEASTERN LOUISIANA^ C. ROBERT SHOOP, Department of Zoology. Tulane University, New Orleans, Louisiana Various aspects of the breeding habits trical shocker. This was the most efficient of several ambystomatids - in the northern method of collecting. United States have been described. Knowl- Two standard temperature readings were edge of the reproductive activities of the made during each visit to the breeding species of Amby stoma endemic to the South- ponds: ( 1 j air temperature 1 meter above east remains fragmentary. Only the eggs the surface, and (2) water temperature and time of breeding of Ambystoma talpoi- (water 10 cm in depth). When specimens deurn have been described. Much of the were found on land, ground surface tem- literature dealing with the mole salamander peratures were recorded at the exact loca- reports only the occurrence of the form in tion of capture. one or more localities. A United States Weather Bureau Cooper- In the region studied, freezing tempera- ative Observer Station, at Slidell, St. Tam- tures are infrequent, and seasonal variations many Parish, Louisiana, close to the study of moisture limiting the activity of sala- area, provided useful climactic and weather manders are less pronounced than those in data. most other parts of the country. Studies of Measurements of total length, body length, the behavioral and ecological isolating mech- and tail length were made with the aid of anisms, of which courtship patterns may be vernier calipers. An ocular micrometer on a part, of the sympatric species of Amby- a dissecting microscope was used for meas- stoma in the Southeast are needed to under- urement of eggs and spermatophores. stand better their phylogenetic relationships. The distance from the tip of the snout The purpose of this study was to obtain to the posterior end of the cloacal aperture detailed information of the breeding beha- constitutes the body length; tail length is vior of Ambystoma talpouienm in southeast- the distance from the posterior end of the ern Louisiana. vent to the tip of the tail. Each measure- Studies of the breeding habits were con- ment is estimated to be accurate within 1.5 ducted both in the field and in the labora- mm. tory from October, 1957, through March, Specimens collected during the 1957-58 1959. Occasional visits were made to the breeding season were killed in ten percent field area during the winter of 1959-60. formalin before hardening and preservation. Those collected and preserved during the MATERIALS AND METHODS 1958.59 and 1959-60 seasons were killed Juvenile and adult Ambystoma talpoide- in ten percent isopropyl alcohol before pres- um were collected by seining and dip-net- ervation. All specimens were hardened and ting in ponds and ditches and random turn- preserved in eight percent formalin. Repre- ing of sticks, logs, paper, and boards on sentative series collected during this study land. Immediately before ponds filled with have been placed in the Tulane Collectiors. water, adults in breeding condition were jhe ovaries of gravid females consist ai- captured by raking the moist floor of the ^^^, entirely of mature ova. Counts of ova pond depression by hand. During the ^ere made in excised ovaries. Tlie ova breeding season of 1959-60 specimens were ^ere carefully teased from the ovary, count- collected with the aid of a 230 V. AC elec- ed with the aid of a hand tabulator, and 1 Awarded the Stoye prize as the best deposited in the Tulane Collections, student paper in Herpetology at the 40th Night observations were made with the annual meeting of the American Society of aid of bright and dim flashlight illumination Ichthyologists and Herpetologists. Ur^.u ;„ ^1° r-^u j ■ j o TT^^ „t„ -p +u A A \ \. i. 4.- both in the rield and in an outdoor concrete - 1< or usage 01 the emended Ambvstomati- . „ _, . dae rather than the conventional Ambysto- P^^ on the lulane campus. The entire court- midae, see Tihen (1958:1 footnote). ship activity was observed using a dim 66 Tulane Studies in Zoology Vol. 8 flashlight, the lens of which was covered by red cellophane simulating the photog- rapher's red light used by many authors in observing the courtship dances of salaman- ders (cf Kumpf and Yeaton, 1932). A single natural study area was utilized for this investigation. It is designated "Si- ren Ponds", and is in St. Tammany Parish, Louisiana, three and one-half miles west- northwest of Slidell, at about ten feet above sea level. The area consists of two sep- arate ponds adjacent to a road. The larger pond, North Siren Pond, reaches a size of 30 by 25 meters and a depth of about 1.5 meters at full capacity. The smaller pond, located about 30 meters south of North Siren Pond is designated as South Siren Pond and is L-shaped, measuring approxi- mately 15 meters in length and 10 meters on the shorter leg. South Siren Pond varies from one to four meters in width and up to one meter in depth during high water. During the summer and fall of 1958 large portions of North Siren Pond were destroyed or disturbed by roadbuilding op- erations. Several mole salamanders collect- ed during the 1959-60 breeding season ex- hibited body damage and regenerated limbs and tails indicating that the disturbance af- fected at least a portion of the population. The roadbed, composed primarily of clay, erodes during rains, and the water through- out most of this pond in early 1959 was extremely murky. Water samples kept un- disturbed in the laboratory required over ,i month to settle. Within and around North Siren Pond proper arc live oak (Onerous virginiana), sweet gum iLitjiiicUinibar styraciflua), and southern hackberry (Celtis mississippiensisi trees. Within and around South Siren Pond are loblolly pine tPiniis taeda) and a few small sweet gum. The land surrounding the ponds is heavily forested with loblolly pine. Dead pine needles cover tiie floor of the forested area in some places to a depth of almost a meter. Few shrubs are present, although greenbrier (Sviilax spp. ) is pres- ent in large colonies. Grasses are present in the more open areas. Burrowing mam- mals and their extensive tunnels are found in the decaying pine needles. The sm.ill burrows are probably constructed by shrews, (Blarina brevicauda and Cryptotis parva) and cotton mice I Peromyscus gossypinus). Other mammals present in the area are skunks I Mephitis mephitis i. opossums iDi- delphis mars/ipialisi, swamp rabbits iSylii- Ligus cicjuaticus), and gray squirrels (Sciurus Ccirolinensis). Within the two ponds is a variety of poikilothermic vertebrates mcluding siren I Siren intermedia), newts (Diemictyhts viri- descens), green frogs (Rana clamitansi, leop- ard frogs, (Rana pipiensi. cricket frogs ( Acris gryllus). chorus frogs (Pseudacris tri- seriataj. mud turtles (Kinosternon suhru- bruml. pigmy sunfish, ( Elassoma zonatuml. and mosquito fish (Gamh//sia af finis I. At times of overflow, black bullheads (Ictaluriis melasi and very small largemouth bass ( Mi- croptertis salmoides) are present. Fairy shrimp, crawfish, back swimmers, diving beetles, leeches, and other invertebrates are common. Many observations were conducted in a rectangular concrete pit 2.32 by 1.52 meters and 0.68 meters deep on the Tulane campus. Water depth was varied to suit the particu- lar experiment. The sides were vertical and the floor sloped slightly to a drain. An overflow drain prevented the water level from rising above 0.53 m. A certain amount of debris (sticks, twigs, catkins, and leaves) continually fell into the pit. Aquaria of several sizes were utilized for laboratory studies. Water in the aquaria was filtered and aerated. Fine gravel was used as a substrate with Anacharis sp. as the only vegetation. The room in which the aquaria were kept was 20 C. ± 2°. Results and Discussion Breeding Season The breeding period. — Professor F. R. Cagle ( personal communication ) recorded breeding of Ambystoma talpoidei/m from early December until the middle of Febru- ary for the years 1949 through 1955 at the Siren Ponds. Gentry ( 1955) remarked that A. talpoideum deposits eggs during January or February in Tennessee. Allen (1932) witnessed A. talpoideum "breeding" in Hen- derson County, Mississippi on February 12, 1930. Carr (1940) collected breeding adults in Alachua County, Florida on February 14, 1933. Mosimann and Uzzell (1952) found breeding adults in Dorchester County, South Carolina on December 31, 1951. Apparent- ly throughout the greater portion of its No. Shoop: Breeding of Ambystoma talpoideum 67 Figure 1. Average monthly temperature in degrees Fahrenheit (solid line) and total monthly precipitation in inches (dashed line) from September, 1957 to April, 1959 as re- coded by the U. S. Weather Bureau at Slidell, Louisiana. 75 70 - BREEDING , PERIOD , 1 1 65 1 60 - fj \l I 4 55 1 Mi AV 50 - \ 3 45 \ \ \\r 40 - w \f \\ 2 35 - V u 30 - . 1 1 25 ■ I II L 1 10 15 20 25 30 5 10 15 a.' DECEMBER, IP 57 JANUARY, 1958 i Fig-ure 2. Average daily temperature in degrees Fahrenheit (solid line) and total pre- cipitation in inches (darkened columns) recorded at Slidell, Louisiana, for the period De- cember 10, 1957, through January 17, 1958. The breeding period of Ambystotxa talpoi- deum is indicated. 68 Tiilane Studies in Zoology Vol. 8 range, the mole salamander is a winter breeder, although the length of an individ- ual breeding period has not yet been re- ported. In 1958, breeding activity in the Siren Ponds began on or about January 6, as judged by the appearance of eggs found on January 8. This breeding period ended by January 12, when intensive efforts to collect mole salamanders in the ponds were fruit- less. Tlius the reproductive activity appar- ently covered a span of seven days. The breeding period of 1959 lasted for eight days, January 30 to February 6. Breeding adults were found in North Siren Pond on January 8, I960. On January 23, I960, two adult mole salamanders in breeding condi- tion were located by the electrical shocker in the same pond, indicating a possible breeding period of 15 days. Clhnatic factors influencing the breeding periods — Weather conditions during the two breeding seasons of this study varied consid- erably. A relatively large amount of pre- cipitation throughout the late summer and fall of 1957 filled the ponds by November 1957. Precipitation was relatively sparse in the late summer and fall of 1958 (fig. 1); no water was present in the ponds until January 30, 1959- The average air tem- peratures during the first fall and winter of this study were lower than those a year later ( fig. 1 ) . On December 30, 1957, there were no salamanders in the pond or under logs sur- rounding the pond. Rains had occurred one and three days previously, and tempera- tures were relatively warm during those rains (fig. 2). Precipitation occurred on January 6 and 7, 1958 with accompanying cold temperatures; breeding activities began at this time. As soon as the ponds began to fill in 1959, and lower temperatures and rains co- incided, breeding took place ( fig. 3 ) • Water and air temperatures in 1959 were higher Fijjure 'i. Aveiajre daily temperature in doyrees Fahrenheit (solid line) and total daily precipitation in inches (darkened columns) recorded at Slidell, Louisiana, for the period January 10, 1959, throufrh February 17, 1959. The breeding- period of Ambystoma talpoi- deiun is indicated. No. 3 Shoop: Breeding of Amby stoma talpoideum 69 Table 1. Summari) of collections at the Siren Ponds during the h)-eedi)iy seasons of 1957-58 and 1958-59 Number Number of of Total Males Females Adults Water Col- Col- Col- Time Tempei •ature °C Depth Date lected lected lected (PM) Water Air (in cm) Dec. 30, 1957 0 0 0 8:15-9:00 16.0 14.0 30 Jan. 8, 1958 2 1 3 8:30-9:30 4.5 —1.1 58 Jan. 9, 1958 2 1 3 8:00-9:30 6.0 2.5 58 Jan. 10, 1958 12 11 23 7:30-8:30 7.0 6.5 60 Jan. 11, 1958 6 4 10 5:30-7:15 10.0 11.0 60 Jan. 12, 1958 0 0 0 8:30-9:30 11.0 15.0 73 Jan. 13, 1958 0 0 0 8:30-9:30 12.0 15.5 79 Total 1957-58 22 17 39 Jan. 30, 1959 11 5 16 8:00-9:20 15.5 12.5 15 Jan. 31, 1959 2 1 3 3 00-4:30 15.5 15.0 15 Feb. 2, 1959 2 6 8 8 30-9:30 10.5 11.5 22 Feb. 4, 1959 25 11 36 8 20-9:20 9.0 7.0 25 Feb. 6, 1959 2 1 3 8 30-9:30 11.0 11.0 26 Feb. 8, 1959 0 0 0 5 45-7:00 18.5 22.0 15 Total 1959 42 24 66 than those during breeding activities in 1958. The largest collection of individuals during one evening in 1959 occurred when the water temperatures were the coldest of the year and approached those of the pre- vious year ( Table 1 ) . The factors constituting a stimulus to breeding in southeastern Louisiana are com- plex. Heavy rains and lower tempera- tures apparently interplay in stimulating the breeding of A. talpoideum (figs. 2, 3). During the breeding season of the years 1957 through I960, moderate to heavy rains were associated with breeding activity. If low temperature is unimportant, the heavy rains of December 27 and 29, 1957, should have been sufficient stimulus for breeding to occur. At that time, temperatures were seasonally normal and the ponds contained water. No breeding activity resulted, but when rains and relatively cold tempera- tures coincided (January 6, 7, 1958), breed- ing commenced (fig. 2). During the win- ter of 1958-59, when the ponds were un- seasonably dry, breeding was delayed until water was present. When breeding oc- curred, the temperatures were not as low as those of the previous year. This observa- tion would seem to indicate that only cool temperatures are needed, or that the lack of water in the ponds forced the adults to utilize conditions which were not optimum. Breeding Adults Males. — The cloacal region of the male swells and becomes protuberant ( figs. 4, 5 ) during the breeding season. The tail be- comes finned (as in other ambystomatids), and the tip of the tail is oar-shaped. A rough, glandular appearing area located dor- so-laterally on the tail is prominent. Sala- manders kept in the concrete pit after breed- ing lost the pronounced tail fin within one to two weeks. The cloacal swelling recedes after one to three weeks. Of 88 males from the breeding pond, the largest specimen (TU. 13589-5) col- lected in North Siren pond during the breeding season, was 122 mm in total length (body 66).^^ The smallest breeding male was 83 mm in total length (body 48). The body lengths of 88 breeding males varied from 48 to 68 mm (mean, 57.2 mm). The tail lengths of 83 males made up 38 to 47 per cent of the total length (range, 33 to 3 The tail is somewhat fragile and was broken or injured in several individuals. In starved animals or adults collected in sea- sons other than winter, and having- no fin, the tail is proportionately smaller than in breeding adults. For these reasons, I con- sider body length a moi-e valid measurement than total length. However, total lengths and tail len^hs are presented for compari- sons with measurements given by other au- thors. 70 Tuhwe Studies in Zoology Vol. 8 Figure 4. Dorsal view of two A mlii/stiiniii tdliioidcnin in ln-eedinj>- condition. Left, fe- male; liK'it. male. No. 3 Shoop: Breeding of Ambystoma ialpoideum 71 ^1 Figure 5. Ventral view of two Ambystoma talpoideum in breedino- condition. Left, fe- male; right, male. 72 Tulane Studies in Zoology Vol. 8 56 mm; mean 42.7 mm) (fig. 6). Fernales. — A slight swelling of the cloacal region is evident in the breeding female, al- though the amount of protuberance is much less than tliat of the male ( figs. 4, 5 ) . The tail fin is somewhat pointed at the distal end. A dorso-lateral glandular area on the tail, such as found on males, is much re- duced. If the adult is kept in water the fin is lost within one to two weeks after court- ship. Of 52 females from breeding aggrega- tions in the Siren Ponds, four had a total length of 111 mm, the maximum for this series (mean, 96.6 mm). The smallest total length was 81 mm (body 46). Body lengths of the females ranged from 46 to 67 mm (mean, 59.5), and tail lengths ranged from 3.^ to 48 mm (mean, 41.0 mm) constitut- ing 37 to 46 per cent of the total lengths. Sizes of males and females combined. — The mean total length of 135 breeding adults (83 males and 52 females) was 99.5 mm and the mean tail length was 42.0; the average body length of 140 breeding indi- viduals (88 males and 52 females) was 58.0 mm. The maximum total length of adults according to Bishop ( 1947) is 97 mm; Conant (1958) noted "3 to 4 inches." Many individual A. talpoideum measured during this study were considerably larger. The male measuring 122 mm in total length represents a record size for the species. The size range of both males and females is great (fig. 6), perhaps indicating that breeding populations may be composed of several age groups. Coloration. — Coloration of any individual may change during a given period of time. When the adults are removed from the breeding pond, a color pattern is barely discernible. The back and sides are liver color with light flecks, fading into blue- gray on the ventrum. If kept in captivity for some time, the animal becomes blue- gray dorsally and lichen-like markings de- velop on the dorsum. Except on very young specimens, a light brown or tan area is present on the dorsum of the tail and occa- sionally on the back of the head. Young specimens invariably liave a dark median stripe on the belly. The Breeding Aggregation Composition of the breeding aggregate. — All specimens collected within the ponds during the breeding season were sexually mature. One sexually immature individual was collected near the ponds during the breeding season. No distinct size groups can be seen in this sample, although the smallest individu- als are probably young adults breeding for the first time. Many of these young adults possess vestiges of the larval belly pattern {i.e. a dark median belly stripe). The find- ing of a single immature specimen during breeding season indicates that at least some of these salamanders do not breed during the first breeding season following meta- morphosis. Males are more common in the breeding ponds at the onset of reproductive activities. They may continue to be more numerous than females throughout most of the breed- ing period ( Table 1 ) . Spent females were observed leaving the pond during the breed- ing period, showing that females leave the breeding pond soon after laying their eggs. Males apparently remain for the entire peri- od. Undoubtedly, both males and females continue to enter the pond throughout this time. Non-continuous sampling of the breeding population might give erroneous indications of the sex ratio. Blanchard (1935) emphasized that in the determina- tion of the relative numbers of the sexes, exclusion of adults is necessary because of differences in habits, and only juveniles should be used for the determination. Behavior of individuals in the breeding aggregation. — Twenty days prior to the breeding activities of 1959, one male was collected under a board near North Siren Pond. There had been rain two days earlier, but no water was present in the pond. Dur- ing a light rain ten days later three males and two females were found in the moist floor of South Siren Pond. Evidently the adults are near the ponds before reproduc- tive activities commence, and during unusu- ally dry winters, they presumably may bur- row in the pond floor prior to the breeding period. Individuals in the breeding pond often burrow in the debris covering the floor during daylight hours. At night, they may be found in every part of the pond; no dis- No. 3 Shoop: Breeding of Ambysfoma talpoideum 73 15 10 i-i Q Q o OS Cd s - 10 45 Figure 6, Body lengths of ments are in mm. 50 55 60 65 70 BODY LENGTH males and 52 females in breeding condition. Measure- tinct preference is shown for a certain depth of water. A congregation of females was detected during the breeding period of 1958 in a region of the pond where large num- bers of twigs and sticks were located. These females were probably laying eggs in this region. All individuals invariably shy from the light of a flashlight if they are not courting. Adults in captivity attempt to hide during the day. Lower temperatures are apparently pre- ferred for breeding purposes (figs. 2, 3). The largest concentration of adults was found when water temperatures were low- est. No breeding adults were found in the ponds in water warmer than 16° C (Table 1 ) , although warmer water was utilized for breeding in captivity. Two spent females were collected from water with a thin ice coat near Hickory, Louisiana, on January 8, 1958. Courtship Pattern Courtship was not observed in the field. On January 30, 1959, two pairs were found following each other about the edge of the pond. Subsequently, four males and four females collected on this date and kept ♦■'- frigerated until February 3, were placed ia the concrete pit on the Tulane campus. Water depth ranged from 4 to 22 cm due to the slanting floor. The water tempera- ture was \1° Q. A small amount of debris consisting of leaves, twigs, larger sticks, a concrete block, and a brick was scattered about on the floor of the pit. Observations from 7:00 PM to 9:30 PM using a dim flashlight showed no courting activity. The individuals seemed to shy from the light. At 8:00 AM the following morning, two 74 7 iiLme Studies in Zoology Vol. 8 dusters of eggs, containing 1 1 and 1 3 eggs, respectively, were found on a small twig in the deepest water. By 3:30 PM, 18 more eggs were found on leaves and on the bot- tom of the pit. Occasionally the adults would move about and swim to the surface to gulp air. At 8:00 AM on February 5, the debris on the floor, and the walls were covered with small clusters of from 2 to 22 eggs. Spermatophores were common on the floor; ten spermatophores were collected, measured, and preserved. This was the first indication that captive specimens would court. During the evening of February 6, the egg laying of several females was ob- served. At noon on February 7, all eight sala- manders were removed from the pit. At this time two females collected on January 30 and 31, and kept in a refrigerator at 6° C, were placed in the pool. Two males, which had been kept in the pit previously and two males collected January 30 and kept at 6' C. since capture, were released in the pit at 6:15 PM. A dim flashlight cov- ered with red cellophane was used to ob- serve these salamanders continuously from 6:15 until 10:00 PM. No unusual move- ments were observed until 7:15 PM. At this time a male began bumping the head of a female with his snout. Air tempera- ture at this time was 17 C while the water temperature was 14° C. From this time un- til observations ceased at 10:00 PM, court- ship activity occurred almost continuously. Nine separate courtship dances were ob- served during the evening of February 7. Only two dances resulted in sperm transfer. All spermatophores were removed from the pit the morning following observations of the dances. No subsequent spermato- phores were found in the pit, indicating that courtship, at least of the females in the pit, had ended. On February 20, ten pairs of adults col- lected on February 4, and kept refrigerated, were placed in the pit to verify previous observations and to provide eggs for fu- ture studies of larvae. On removal Febru- ary 27, only 14 individuals were in the pit. The tail fin was reduced in all of them and the cloacal swelling of males was lessened. All six missing individuals were females. Courtshtp. — After bumping the female for about 10 seconds (fig. 7A;, the male runs ills head along the sides of the female to her cloacal region. The female begins nosing the cloacal region of the male and both of them push with their heads. This results in a circular movement or "waltz" of one or two revolutions (fig. 7B). The male here breaks contact with the female's cloacal region and begins to straighten his body. The female slides her head down to the tip of the male's tail. Thereupon the male begins a peculiar wagging of the pelvic region and proximal portion of his tail while keeping the posterior part of the tail undulating and often touching the female's head (fig. 7C). At this time his cloacal aperture opens and the spermatophore stalk may begin forming. Using the front feet for propul- sion the male moves forward slowly con- tinuing the wagging motion. The female follows, keeping her head in contact or in close proximity to the male's tail. After one to eleven minutes of following, the female pushes her head along the male's tail until she reaches his cloacal region or hind legs. At this time she bumps the male ( fig. 7D ) on the cloacal region one or two times and the male ceases the pelvic movement. With the hind legs directed outward and posteriorly, the male deposits a spermatophore ( fig. 8A ) . If he does not stop his movements, the female returns to the distal end of his tail. Immediately after deposition the pelvic motion is resumed. The female noses the spermatophore and slowly begins to crawl over it (fig. 8B), the male keeping his tail near the female. If the female is led by the male to a position in which her cloaca is directly over the spermatophore, she will assume the same posture taken by the male in depositing the spermatophore and, using her cloacal lips, pick up the entire spermatophore or clip off the sperm cap ( fig. 8C ) . Rarely does the male so lead the female. If the female successfully picks up a spermatophore or cap, immediately after or within a minute or so, she loses interest in the male and wanders away from him (fig. 8D ) . The male continues his wagging movements for several minutes. If a successful pickup is not made, the female continues to follow the male imtil such occurs or until the dance is terminated, usually when the pair becomes separated. One female was ob- No. 3 Shoop: Breeding of Amby stoma talpoideum 75 B Figure 7. Courtship pattern of the mole salamander. A, male noses female; B, the "waltz"; C, female follows male; D, female bumps the cloaca of the male. served to be unsuccessful in seven attempts to pick up a spermatophore, finally leaving the male courting her. The pair moved a distance of over seven feet during this courtship dance. A female may be courted by many males and offered many spermato- phores before she picks one up. Females will pay no attention to spermatophores un- less they are offered during courtship. At times another male may join the dance and will push between the original male's tail and the female's head, thereby separat- ing the pair engaged in the dance. The in- truder then begins courtship by bumping the head of the female and following the above pattern. In this case, the rejected male continues the pelvic motion for some minutes. Use of a weighted sponge with Tidane Stiulies in Zoology B Vol. 8 Figure 8. Courtship pattern of the mole salamander. A, male deposits a spermato- phoi"e; B, female noses spermatophore; C, female picks up spermatophore or spermato- phore cap; D, female leaves male. female secretions in the manner described by Twitty (1955) yielded no results. Ap- parently, meeting of the males and females is haphazard. Total time for courtship dances ranged from seven to thirty-seven minutes. The shorter dances may have been terminated because of the use of flash bulbs in photo- graphing the courtship. affect of light. — Dim light (red or white) has little effect on tlie courting individuals. Bright light will cause the participants to stop all movement. If the bright light is removed quickly, the courtship will contin- ue. Any light, no matter how dim, may cause non-courting individuals to shy away. Spermatophores A male placed in an aquarium at 20° C without females deposited two spermato- phores, indicating that courtship is not nec- essary for deposition. Males injected with No. 3 Shoop: Breeding of Ambystonia talpoideum 11 four female Kanu pipiens pituitaries, as sug- gested by Noble and Richards (1932), be- gan depositing spermatophores within 48 hours. The total observed number of sper- matophores produced during courtship by an uninjected male was fifteen. Figure 9. Spermatcphore of Amhystoma talpoideum. Left, side view; right, top view. The spermatophore has a wide circular base with a relatively thin stalk tipped by a sperm cap ( fig. 9 ) . All spermatophores were attached loosely to the pool or aquari- um floor. The jelly-like base is clear and gelatinous, while the sperm cap is cottony white. The general shape of the cap is a flattened ellipsoid, but is variable and may be almost spherical. On the top, a slight fold runs from the anterior to the posterior end dividing the cap into two approximate- ly equal halves ( fig. 9 ) . The jelly-like stalk has a blunt apex and a relatively wide base. The total height ranges from 6.3 to 8.5 mm; stalk length 3.6 to 6.6; base width 5.1 to 8.2; stalk at narrowest point LO to 2.5; cap depth 1.0 to 2.6; cap length 2.6 to 3.1; and cap width 2.0 to 2.9. Several spermatophores were examined microscopically the morning following dep- osition. The cap was found to be composed of cellular strands of two sizes. Apparently spermatozoa should have been found be- tween these strands, but none was seen. Between the strands may be found extremely abundant colonies of protozoa ( Sarcodina, Ciliata, and Mastigophora ) , vegetative hy- phae of a phycomycete, and filaments and individual cells of green algae. The gelati- nous stalk contains lesser quantities of these organisms. Oviposition Courtship is not a ne:essary prelude to egg laying. Females collected on land be- fore the breeding season may lay unferti- lized eggs when placed in aquaria at room temperature (20° C). This phenomenon occurred with all three females tested, but Professor Cagle (personal communication) kept several gravid females in aquaria two months and oviposition did not result. A female placed in a terrarium containing only damp sand resorbed her eggs. The appearance of the ovaries of this female was essentially like those of Ambystoma jeffersonianum. described by Clanton (1934). Infertile eggs apparently are rare in nature as only one was observed. Under condi- tions in the concrete pit, several clusters contained one to many unfertilized eggs. Oviposition usually takes place at night, but one female was observed to lay eggs in the outside pit during a cloudy afternoon. Eggs may be laid on any substrate in the breeding pond, but there is a decided preference for small twigs approximately one-eighth inch in diameter which are oriented at an angle to the surface. No definite preference was shown for a par- ticular water depth. Areas containing many twigs and sticks seem to be preferred. Eggs were sometimes deposited on twigs near the surface of the pond at times of high water and, with the lowering of the water level, left hanging in the air. Positions assumed during oviposition vary, depending on the substrate and its orienta- tion in relation to the surface. If ovipo- sition occurs on the bottom of the pit, the female assumes a position in which the cloacal lips are pressed firmly to the sub- strate and begins to wave the tail slowly. When the waving decreases or ceases one to several eggs may be deposited. If the female does not move during deposition, the form the eggs will assume after water absorption is a large spherical clump; if she moves slowly during deposition, using all four feet, the eggs will appear after water absorption as a long, single strand. Several individuals have been observed laying eggs on the vertical walls of the con- crete pit. The female's head is always pointed toward the surface and a grip on the roughened concrete is kept by all four feet. The tail undulates slowly before the initial deposition. The female appears to rest after laying one to six eggs; during this time, the rail waving is resumed. After 78 Tulane Studies in Zoology Vol. 8 laying a clump of eggs the female returns to the floor of the pit. If a twig is oriented at an angle to the surface of the water the female will swim up to the twig at a point about 10 to 15 cm from the floor, and grasp it with her hind legs. While waving her tail, she gradually turns under the twig with ven- trum up. Using only the hind legs and feet for traction, she moves slowly along the twig toward the surface depositing eggs. The tail undulates slowly except during ac- tual deposition. The trunk of the body may at times be nearly at a right angle to the twig. By alternately shifting the tail and body, and moving slowly between times of deposition, the eggs may be laid in a wave- like pattern along the underside of the twig. This method of laying was observed frequently, and many eggs in the natural pond because of their location on twigs appeared to have been laid in this fashion. Females do not always turn over to lay eggs on slanting twigs. The eggs are laid in small clusters. Often many clusters appear on the same twig. These clusters may or may not be laid by one female. On one occasion a female was seen laying eggs between clusters of eggs deposited previously by another female. The number of eggs in 75 individual clusters ranged from one to 37. One marked fe- male laid eggs during three consecutive nights in the concrete pit. More than one night is probably required for all the eggs to be laid. Two females took 15 and 22 minutes to lay 17 and 18 eggs, respectively, before returning to the bottom where they remained motionless for more than an hour. Only one series of adults collected on land before the breeding season is in the Tulane collections. This series (TU 13584), consisting of 33 specimens, was collected near the Siren Ponds on the same day, before water was present in the ponds. Fourteen are females containing enlarged ova within the ovaries. The number of ripe ova of each specimen varies from 226 to 401. From figure 10, one can see that the largest individual or the smallest did not produce the largest or smallest number of eggs, re- spectively. More data are needed to show a correlation, if any, between length and size X H O sc u *i s« a o aa 250 300 NUMBER OF EhfLARGED OVA 3 50 400 Figure 10. Graphical representation of body lenfcth in mm plotted a<. Jour. Exp. Zool., 129 ( 1 ) : 129-148. Wilder, Inez W. 1924. The developmental histoiy of Eiirifcea hisUueata in western Massachusetts. "Cope/o, 1924, No. 133: 77- 80. Wright, A. H., and A. A. Allen 1909. The early breeding habits of Ambystoma punctatitm. Amer. Nat., 43: 687-692. Abstract Breeding habits of a population of mole salamanders, Ainbij.'tto)na falpoi- denm, were studied near Slidell, St. Tammany Parish, Louisiana. Only sex- ually mature individuals moved to the ponds to breed during a period of six to fifteen days during the winter. Breeding was coincident with rain and low temperatures. The courtship be- havior was described and compared with that of other members of the genus. The courtship pattern was most like that of the nearest relative, Amby- stoma opacinn. The spermatophore of A. talpoideuni is distinct. SALINITY RELATIONS OF SOME FISHES IN THE ARANSAS RIVER, TEXAS' WILLIAM C. RENFRO, U. S. Bureau of Commercial Fisheries. Biological Laboratory, Galveston. Texas Introdiiction Fishes inhabiting bays and estuaries along the lower Gulf coast of Texas are at times subject to extremes in temperature and sa- linity. During droughts evaporation is high and salinity tends to increase during most months of the year. A question often dis- cussed is: What part does salinity play in affecting distribution and abundance of fishes inhabiting this area.'' Seyeral workers have studied salinity re- lations of fishes in the inshore waters along the eastern and southern coasts of the United States. Hildebrand and Schroeder (1928) studied the fishes of Chesapeake Bay and included salinity records in many of their observations. Gunter (1945) published an extensive account of the distribution of the marine fishes of Texas as related to salinity. Gunter (1950) studied distribution and abundance of fishes in marginal ponds and salt flats in the Aransas National Wildlife Refuge with emphasis on changes due to temperature and salinity. The latter two studies were made during periods of normal or above normal rainfall. Simpson and Gun- ter (1956) described the effects of salinity on Gulf coast cyprinodonts during an ex- tremely dry period. Simmons ( 1957) studied the problem in the usually hypersaline La- guna Madre of Texas. Reid ( 1954) surveyed ecological relations of the fishes near Cedar Key, Florida. Reid (1955, 1956, 1957) published accounts of the changes in abundance and distribution of fishes in East Bay, Texas, before and after construction of an artificial pass connecting the blind end of that bay with the Gulf of Mexico. Kilby ( 1955) studied the fishes of Cedar Key and Bayport, Florida, and the extent to which salinity affected their distri- bution. Bailey, Winn, and Smith (1954), in their accounts of the fishes of the Escam- 1 Part of a thesis presented to the Fac- ulty of the Graduate School of the Univer- sity of Texas in partial fulfillment of the requirements for the degree of Master of Arts. bia River, Alabama and Florida, recorded sa- linity relations of many marine and fresh- water fishes. Because abrupt salinity strati- fication occurred in the Escambia River at times, Bailey et al. ( 1954) were not always able to determine the exact salinity in which some of their specimens were living. Spring- er and Woodburn (I960) discussed the effects of salinity, temperature, and vegeta- tion on the distribution of fishes in the Tampa Bay area. The objective of this study was to note the occurrence of fishes found at three stations on the Aransas River under conditions of varying salinities. The study began during September 1956 at the height of one of the worst droughts ever recorded for this section of the United States. Field work was concluded in November 1957, six months after the drought was broken by heavy rains which fell during the summer of 1957. Two aspects which previous authors have not had an opportunity to study extensively are emphasized in this paper. First, the populations sampled came from habitats in which salinity was an im- portant variable. Secondly, variation in sa- linity occurring in the river provided oppor- tunities for study of the interaction of fresh- water and marine fishes. Description of the Area The Aransas River has its source at ap- proxim^ately latitude 28M7'N. and longitude 97 ° 40' W. It terminates at Copano Bay, which is connected to the Gulf of Mexico through Aransas Bay and Aransas Pass (fig. 1 ) . Except for drainage of water after rains there is no net seaward flow. Water stands only in the lower 28 miles of the river bed as the result of ground water addition and backup of water from the secondary bays. The river averages 100 feet in width and about 3 feet in depth although occasional deep holes may range to a depth of 15 feet. Vegetation in the river was scanty, prob- ably as a result of extremes in salinity. Along certain stretches of the banks were 84 Tillable Studies in Zoology Vol. 8 found emergent plants such as sedges, water hyssops, willows, rushes, grasses, and pond- weeds. Dominant algae were a blue-green alga, Pbormidiiun sp., and a green alga, Cladophora sp. The amount of this algal vegetation increased during the latter half of 1957 with the advent of increased pre- cipitation and lowered salinities. Salinity of the river appeared to be con- trolled by: (1) precipitation, (2) evapora- Methods Stations were sampled every 4 to 6 weeks at which time air temperature, water tem- perature, weather conditions, and vegetation were observed. Samples of water to be mea- sured for salinity were taken at the surface and at a depth of 2 feet. Salinity was de- termined by titration with silver nitrate. Table 2 summarizes temperature - salinity conditions observed at the three stations. GULF OF MEX IC 0 0 9 10 STaroTE MILES Figure 1. Central Texas coast showing location of study area. tion, (3) intrusion of salt water from Co- pano Bay, (A) invasion of highly saline water from Chiltipin Creek which was pol- luted with brine wastes from oil fields. Salinities found at each station during the study are shown in Figure 2. Precipitation was recorded at Beeville, Texas, which lies in the middle of the watershed. Figure 2 shows that small amounts of rainfall merely dilute the saline water in the river while periods of heavy rainfall cause floods which flush it into the bays. During April, May, and June 1957 the two lower stations were not sampled due to impassable roads. No attempt was made to sample all fish species present in the river. The data pre- sented concern only those fishes which could be sampled within a limited area and depth along the shore. The same 30-foot bag seine was used for all collections. It was 4 feet high with wings of V^-inch bar mesh and bag of 1 -4 -inch bar mesh. At each station the seine was hauled either once or twice No. Renfro: Salinity Relations of Fish 85 parallel to the shore over fixed paths and distances. All fish taken at a station were immediately preserved in 10 percent for- malin for subsequent examination. All mea- surements are standard lengths to the nearest millimeter. Table 1 summarizes the distri- bution by salinity of the fishes collected. Stations at 9, 16, and 25 miles from the mouth of the river being most accessible were selected as collection sites ( fig. 1 ) . Mile 9 and Mile 25 had gently sloping bot- 60 toms. At Mile 16 the bottom sloped gently for about 8 feet, then more abruptly so that at a distance of 12 feet offshore the depth had increased to 6 feet. The bottom at all three stations consisted of silt and mud. Salinities Recorded for Species Observed Lepisosteus spatula Lacepede, Alligator gar- — Only three alligator gars were taken with the type of gear used although the \ \ ' - \ / — 5 — 6 I CO X — 8 I- < Ql O UJ a: Q. 10 12 0 NOV Figure 2. Salinity regimes — Aransas River, mulative total recorded between collections. M J J A S 1957 Precipitation at Beeville, Texas is the cu- 86 Tulane Studies in Zoology Vol. 8 species was abundant in the river at all times. taken in salinities above 1.1" on. This sup- One specimen approximately 1 meter long ports the conclusions of Gunter { 1945 ) was captured at Mile 25 in October 1956 that the gizzard shad inhabiting coastal in a salinity of 35.2" 'no. Another was taken waters must return to fresh water to spawn, in October 1957 at Mile 25 in a salinity of Only two adult gizzard shad were taken in 0.05" (1(1. It measured 425 mm in length. highly saline water; one measuring 114 mm The third was a small specimen 70 mm was caught in 35.2"/oo and the other, 104 long collected in November 1957 in a sa- mm in length, was taken in 4l.3"/o(i. Unity of 8.3" od at Mile 9. Gars were ob- Dorosoma petenense (Gunther), Thread- served in the river during every month of fin shad. — Thirty-three juveniles were col- the year and in every salinity (0.05 to lected. One specimen 35 mm in length was 58.6" (Id). caught in a salinity of 10.4" .k, at Mile 9 Brevoortia patronus Goode, Largescale during August 1957. All others measured menhaden. — One specimen 120 mm long less than 60 mm in length and were taken was collected at Mile 9 in March 1957 in a in salinities of 1.0' od or lower, indicating salinity of 54.3"/(io. At the same time at that this species also might require fresh Mile 16 another specimen measuring 32 mm water to spawn. was taken in 47.6",'()o. In July 1957 three Anchoa 7nitchiUi (Valenciennes) , Bay an- individuals, 52, 61, and 64 mm long were chovy. — A total of 228 individuals of this found at Mile 16 in 0.5"/(io. species was taken. They ranged from 23 to Dorosoma cepedianum (LeSueur), Giz- 57 mm in length although most were be- zard shad. — Sixty specimens were collected in tween 40 and 50 mm. Bay anchovies were salinities ranging from 0.05" oo to 41.3" od. found in salinities from 0.05" dd to 8.3" dd No juvenile fish were taken in the first and none were taken during 1956 when the half of the study when the river was highly river was hypersaline. saline. Forty specimens less than 40 mm Notropis hdrensis ( Baird and Girard), long were caught in July 1957 in salinities Red shiner. — Three juveniles were collected of 1.1'^/do or less. No small individuals were in August 1957 in a salinity of 1.0" (k,. Table 1. Occurrence by salinity of fishes collected. from: .05 1.1 5.1 15.1 25.1 35.1 45.1 55.1 Salinity ^/(m to : 1.0 5.0 15.0 25.0 35.0 45.0 55.0 58.6 Collections in this salinity range 10 2 3 2 1 5 7 2 Lepisosteus spatula 1 1 1 Brevoortia patronus 3 — — 2 Dorosoma cepedianum 47 0 6 — 2 Dorosoma peteyiense 32 1 — Anchoa mitchilli 114 79 35 Notropis lutrensis 3 fcfaliirns furcatus 1 1 — — Si/)igii(tthHS scovelli 1 143 21 Fioididns grandis 8 11 2 4 17 2 Liicania parva 45 6 19 1 Cyprinodon variegatus 144 12 46 28 11 173 161 13 Gambnsia af finis 22 6 1 4 — — — Mollicti isia latipinna 13 2 61 1 129 1 — Mctiidid h('ri/llii)a 285 124 75 302 484 137 77 7 Miigil cephalus 10 1 18 57 9 30 31 4 Mugil curema 1 Micropteriis salmoides — 1 — — Chac}\(>hrt)ttns gnlosus — Lepo m is ma crock irus 41 8 6 — — Lcpomis mcgalotis 4 — Bairdiella chrysura 2 — Encinostomus argenteus — 3 — — Cichlasoma cyanoguttatum 7 1 4 — Dormitator mac^datus 1 Gobiosoma bosci 1 4 Trinectes maculatus 1 1 1 No. Renfro: Salinity Relations of Fish 87 Ictalurus f meatus (LeSueur), Blue cat- fish.— Two specimens of this fresh - water catfish were taken. One measured 104 mm and was found at Mile 16 in a salinity of 1.0'' (,(,. The second, measuring 85 mm in length, was caught in a salinity of 10.4"/(i(i at Mile 9. Gunter (1945) found a few blue catfish in salinities up to 6.9" do in Copano Bay. Syngnathus scovelli (Evermann and Ken- dall), Gulf pipefish. — In September 1956, 164 specimens were collected from two sta- tions. Twenty-one came from a salinity of 38.1"/oo at Mile 16 and 143 were found in a salinity of 17.4" ,,(, at Mile 25. Nearly all the males were either carrying developing eggs and embryos or had recently delivered broods ( as indicated by their enlarged, flac- cid pouches). One other pipefish, a ripe female measuring 89 mm, was taken in a salinity of 0.06"(io during June 1957. Pipefish are usually found in or near sub- merged vegetation, and salinity might well affect their distribution and abundance by altering the amount of vegetation available to them. Simmons ( 1957) found this species abundant in vegetation in salinities to 45"/oo- Fundulus grandis Baird and Girard, Gulf kiUifish. — Forty-four Gulf killifish ranging in length from 21 to 90 mm were taken in salinities of 0.05 to 58.6" Oo. Table 2 shows that this species occurred throughout a wide range of salinity-temperature combinations. Small and large killifish were found together in both fresh and hypersaline water. Simp- son and Gunter (1956) took F. grandis in salinities varying between 1.8* ^lo and 76.r'/oo. Lucania parva ( Baird and Girard ) , Rain- water killifish. — Seventy - four specimens ranging in length from 9 to 32 mm were collected in salinities from 0.05" dd to 47.6"/()(,. Sixteen were taken at one station in a salinity of 38.1" Oo, and only four were caught in salinities above this. Over 60 per- cent were found in salinities less than lO.O'/o... Gunter ( 1945 ) found this species most abundant in salinities between 10.0" od and 15.0' ,,„. Kilby (1955) took 81 percent of his specimens from waters of 10" on or less. Simpson and Gunter ( 1956) found 39.4 percent of the rainwater fish they collected in salinities below 10.0" „(i, the greater pro- portion having been taken at salinities be- tween 18.4" ,„, and 48.2" o.,. In Florida, Springer and Woodburn ( I960; found this species to be most common in salinities greater than 25" w\. They stated that vege- tation rather than salinity is probably the most important factor affecting its distri- bution. Cyprinodon variegatus Lacepede, Sheeps- head minnow. — A total of 588 sheepshead minnows was collected, accounting for 18.5 percent of all fishes taken. They were found in salinities ranging from 0.05" dd to 58.6" dd- Simpson and Gunter ( 1956) caught 2,- 009 C. variegatus in a salinity of 142.4" dd and stated that, so far as they knew, "this was the highest salinity at which living fishes have been reported." During August 1957 the writer kept one specimen in a small aquarium for 7 days in a salinity of 12 5.2"/ 00 and when the salinity was raised to 145.6" ()o by the addition of sea-salt crystals, it lived an additional 37 hours. However, as Simpson and Gunter lop citi emphasize, "water at such salinity is not sea water for some salts are precipitated before sea water attains such concentration and the salt complex is changed." In December 1957 a pair of C. variegatus kept in an aquarium in the laboratory spawned four eggs. These eggs were trans- ferred to a shallow glass dish 100 mm in diameter and filled with sea water to a depth of 25 mm. The dish was placed in a water-filled pan to avoid rapid changes in temperature and the eggs were observed daily. On the afternoon of the 12th day the eggs had not hatched, but on the mor- ning of the 14th day three larval fishes were found darting rapidly around the dish. They measured 4 mm in standard length and had absorbed their yolk sacs. Evaporation had decreased the depth of the water in the dish to 8 mm and salinity was in excess of 110' dd. Temperature during incubation ranged from 17.4" C to 27.5 "C. Within the ranges recorded, increasing salinity and changes in temperature did not inhibit in- cubation of the eggs and young were able to survive in hypersaline water. There appears to be no correlation be- tween size and salinity as small and large specimens were found in all salinities en- countered. Radical changes in abundance were not noted even during periods of ex- tremes in salinity and temperature (Table 2). 88 Tulane Studies in Zoology Vol. 8 Table 2. Salinity-teviperature coiiditious at three stafious on the Aransas River and the number of individuals of several species taken therein. Date 6/22/57 7/20/57 Station 60 e 2 e Salinity Water temperature o/oo °C fc, s> ^ s. O 5 •S s "S"53 25 0.06 26.2 — 4 90 4 s a. 9 54.9 29.3 1 6 2 9/ 4/56 16 38.1 27.9 3 16 90 95 76 8 25 17.4 29.8 2 7 59 148 2 9 58.2 29.5 1 4 10/14/56 16 25 54.0 35.2 28.0 29.6 3 2 4 9 58.6 16.0 2 13 6 — 11/25/56 16 52.2 16.0 8 1 31 25 41.3 18.6 3 4 34 51 9 50.3 16.0 3 52 6 1 1/30/57 16 43.9 20.5 62 — 1 2 25 11.4 18.9 1 3 58 17 9 49.5 21.0 3 15 — 7 8 3/ 2/57 16 39.0 21.2 1 17 9 16 25 21.0 21.0 2 1 21 2 157 55 9 54.3 21.2 10 — 30 20 9 3/30/57 16 47.6 21.2 2 47 11 11 25 29.5 21.2 6 11 7 1 11 481 2 9 5/ 5/57 25 0.08 24.2 10 — 1 — 25 1.1 34.5 — — — — 101 1 9 10.4 32.9 6 21 1 8/14/57 16 1.0 31.2 7 5 25 1.0 31.2 2 2 2 98 9 0.8 27.2 1 12 13 10/ 5/57 16 0.06 27.0 5 6 25 0.05 29.0 2 1 2 — 9 8.3 24.6 4 22 2 17 11/ 2/57 16 2.7 24.5 12 — 23 25 0.2 24.2 38 17 — 158 Gambusia af finis ( Baird and Girard ) , Mosquitofish. — Thirty-three specimens from 9 to 36 mm long were collected. All but five were taken in salinities of l.I"/o(i or less. In September 1946 four specimens were found in a salinity of 17.4"/oo. During November 1957 one mosquitofish measuring 19 mm was found in a salinity of 8..-5"/ m at Mile 9- Simpson and Gunter ( 1956) caught one G. affinis in a salinity of 20.6"/oo- Kilby ( 1955 ) stated: ". . . it thus appears that the fish is most numerous in protected waters such as shallow pools and vegetated areas where the salinities are lowest, at least periodically, but it can tolerate salinities up to at least 26" ' i,„." Mollienisia lafipinna LeSueur, Sailfin mol- ly.— Two hundred and seven individuals ranging between 12 and 44 mm in length were caught in salinities of 0.08" „„ to 52.2"/oo- This species is ordinarily found in schools and thus capture is, for the most part, fortuitous. In fact, three seine liauls accounted for more than 90 percent of the specimens collected. Herre (1929) noted the remarkable .salinity tolerance of M. latipinna in popula- tions which had been transported from the United States via the Hawaiian Islands and accidentally naturalized in the Philippine Islands. He found the species to be abund- ant in .salinities from 32" no to 87*^' oo, and that the latter salinity appeared to be near No. Renfro: Salinity Relations of Fish 89 its limit of toleration, for in ponds with a salinity of 94"/ oo, it had entirely disappeared. MenJclhi beryllina ( Cope ) , Tidewater sil- verside. — A total of 1,491 individuals was collected. The tidewater silverside is prob- ably the most abundant species in the area sampled. They were found in salinities from 0.05" oo to 58.6", oo and in widely differing combinations of salinity and tem- perature. Collections taken over a wide range of salinities had both small and large specimens in fairly constant ratios. Gunter ( 1945 ) found specimens of M. beryllina to be slightly larger in waters above 25" od than in those below that salinity. Mugil cephalus Linnaeus, Striped mullet. — One hundred and sixty striped mullets were collected during this study. Adult mul- lets easily escaped the collecting gear used, and only six specimens captured were more than 100 mm long. The great majority were juveniles measuring 22 to 42 mm taken from March to May 1957. Juveniles were found in salinities ranging from 0.08"/oo to 54.3"/oo- Larger mullets were observed jumping in the river during every month and in every salinity encountered. Mullets at all ages are euryhaline. Since it is difficult to separate immature M. cephalus and M. curema, it is possible that some of the smaller specimens were M. curema. Mugil curema Valenciennes, White mul- let.— One white mullet measuring 79 mm was taken at Mile 25 in a salinity of 0.2" oo- Its fins were heavily infested with leeches. Micropterus salmoides ( Lacepede ) , Large- mouth bass. — At Mile 25 on September 4, 1956 a largemouth bass 151 mm long was caught in a salinity of 17.4" 'oo- Two other species of the family Centrarchidae and one cichlid species were included in this un- usual collection. It is unfortunate that fur- ther salinity determinations for the upper reaches of the river were not made on this date to determine the salinities these typical- ly fresh -water species passed through to reach this station. Hildebrand and Schroeder ( 1928) reported M. sahnoides from a salin- ity of 12.87"/oo taken at Lewisetta, Virginia, in August 1921. Of the 18 specimens re- ported in Kilby's (1955) collections, only 1 was taken where the salinity reached ll.SVoo- Renfro (1959) concluded that salinities above 9 ' do were progressively more critical, but that this species might be expected to survive several weeks in lower salinities. Chipman (1959) studied fishes in a Louisiana pond which was polluted with oil well brine wastes. He noted mortalities of fresh-water species which died during a 7- day period in which salinity was first re- corded at l6.5"/oo, rose to 20.9" oo on the 5th day, declined to 5.8" d,, and 6.6" /oo re- spectively on the 6th and 7th days. He found one largemouth bass dead in a salin- ity of 20.6 'oo. Chaenobryttus gulosus (Cuvier), War- mouth. — Two specimens measuring 68 and 72 mm taken in the collection mentioned above (salinity 17.4" ,)„) were the only two warmouths observed. During his 7-day study Chipman ( 1959) found 748 warmouths dead. He found in laboratory toxicity experiments that 12 speci- mens tested died in salinities between 10.7" ,,0 and 16.9" do- Leponiis macrochirus Rafinesque, Bluegill. — Six subadults were taken at Mile 25 Sep- tember 4, 1956 in 17.4"/ 00. On November 2, 1957 six young specimens 28 to 35 mm in length were collected at Mile 16 in 2.7" 00- The remaining 43 bluegills taken were found in salinities of l.l"/oo or less and ranged in length from 16 to 83 mm. Chip- man ( 1959) noted 523 dead bluegills during his 7-day study. Leponiis megalotis ( Rafinesque ), Longear sunfish. — Four subadults were taken in col- lections during the latter half of 1957. All were caught in salinities of 0.2*^'/oo or less. Bairdiella chrysura (Lacepede), Silver perch. — Two specimens measuring 86 and 93 mm were taken on November 2, 1957 in a salinity of 2.7" do- Gunter (1945) found this species to be more or less in- different to salinity. Kilby (1955) caught silver perch in salinities from 5.6'Voo to 27.3" 00. Springer and Woodburn (I960) took this species in salinities from 3.7"(io to 35.0" (10 with most being captured in salinities above 20.0" /oo. Eucinostomus argenteus Baird and Gir- ard, Spotfin mojarra. — Three young indi- viduals 40, 41, and 43 mm long were caught at Mile 9 in a salinity of 8.3" do. Species identification of this difficult genus is pro- visional. Cichlasonia cyanoguttatum ( Baird and Girard ) , Rio Grande perch. — Twelve Rio Grande perch were taken during the study. 90 Tulane Studies in Zoology Vol. 8 four being found in the collection of Sep- tember 4, 1956 at Mile 25 in 17.4" ,„,. The remaining specimens were taken at various times in salinities of 1.1" iki or less. Dnrniitator macidatiis ( Bloch ) , Fat sleep- er.— One specimen 38 mm long was caught on September 5, 1956 at Mile 9 in a salinity of 54.9' (i(i. As this species is known to penetrate far inland (Moore 1957) it ap- pears to be tolerant to a wide range of salinit'es. Gobiosoma bosci (Lacepede), Naked go- by.— Five specimens were collected, three being taken in 21.r'/o(), one in 17.4"/on, and one in a salinity of 0.2*Voo- Trinectes macidatits (Bloch and Schnei- der ) .Hogchoker. — Three hogchokers were taken in salinities of 0.8"/oo, 2.7"/no, and 8.3" (!(,. Simmons (1957) stated that the hogchoker was common in salinities of 50 ' 1)11 or less during the fall months in the Laguna Madre. Discussion and Summary During this study salinity in the river varied over a broad range and fluctuations were sometimes rapid. Water levels v.'ere constant except during floods; water tem- peratures observed varied from 16.0° C to 34.5 ° C, and the shore and bottom configu- ration was stable. Most of the species taken were those which are characteristically found along the shoreline, and if must be empha- sized that the conclusions reached do not extend to the fishes which were undoubtedly present in the river but which were not taken with the gear used. As previously stated, the objective of the study was to note the occurrence of fishes in varying salinities. It is felt that the data obtained allow inferences concerning salin- ity tolerances. Salinity tolerance as here used is construed to be the capacity of a fish to endure specific levels of dissolved salts. The writer is aware that the relationship of a fish to its environment is a complex phenome- non. A fish is obliged to adjust not only to changing salinity, but to changes in tem- perature, dissolved oxygen concentration, food supply, and numerous other interrelated parameters of its environment. In the case of critical salinities ( those concentrations of dissolved salts too low or high for the fish to withstand indefinitely ) we might expect exposure time to become a factor. That is, in increasingly more critical salinities, the fish's survival time must decrease. For this reason, it is possible that some of the fishes taken were transients, being found in salin- ities higher or lower than they could with- stand for more than limited intervals. Twenty-six species belonging to 8 orders and 16 families were collected. Nine species (Dorosoma petenense, Notropis lutrensis. Ictaluri/s jurcatus. Gaynbusia affinis, Microp- terus saltnoides. Chaenobryttus gulosiis. Le- pomis megalotis. Lepomis macrochirus. and Cichlasoma cyanoguttatinn) are fresh-water fishes, i.e., they are found in fresh water and occur in salt waters only occasionally or in reduced numbers. Five of these species were found in a salinity of 17.4"/(M), which indicates that they have at least temporar\' tolerance to this salinity. Why then do not these fresh-water fishes occur in greater numbers when the salinit)' in the river has been decreased to a level which they are known to tolerate? Probably they do not because of the innate character- istics of this particular hydrographic system. When salinity is lowered these fishes ven- ture into the lower reaches of the river. Be- fore their numbers can reach significant pro- portions, however, the salinity begins to increase and they are either forced back up- stream or perish. Population densities of these "fresh-water" species appear to vary inversely with salinity. The gar, Lepisosteus spatula, and the clu- peid, Dorosoma cepedianum. were tolerant of all salinities observed and might well be considered euryhaline. Presumably spawn- ing must take place in fresh water. Eight species ( Breioortia patronus. An- choa mit chilli. Syngnathus scovelli. Baird- iella chrysura, Eucinostomus argenteus. Go- biosoma bosci. Trinectes maculatus. and Mu- gil ciircnia) are commonly foimd during part or all of their lives in salinities between fresh water and sea water. With the exception of the goby, all enter the Gulf at times. How- ever, these species are probab'y not well adapted for life in salinities above 35" od. The remaining seven species iFundulus grandis. Lucania pari'a, Cyprinodon varte- gatus. Mollienisia latipinna. Menidia beryl- Una. Mugil cet>hahis. and Dormitator viacu- Lit/is) are particularly fitted for life in a wide range of salinities. They are able to main- tain their populations in the river regardless of changes in sahnity. Most of these species No. Renjro: Salinity Relations of Fish 91 were represented in collections in which Kilby, John D. 1955. The fishes of two salinity and temperature were at extreme Gulf coastal marsh areas of Florida, levels. They are among the hardiest of the /'^l^^'^Stud. ZooL, 2: 175-247. smaller fishes found along the coast of the ^*?^^^' ^•, ^/ ;?57 Fishes. In- Verfe- .^ ,r r nr ■ T-i 1 f 1 r i orates of the Ihuted States, by Blair, et Gulf of Mexico. These are the fishes found al. McGraw-Hill, New York, pp. 33-210. most often and in greatest aboundance along Reid, George K.. Jr. 1954. An ecological the shorelines of inside waters of the north- study of the Gulf of Mexico fishes in the western Gulf of Mexico. vicinity of Cedar Key, Florida. Bull. Mar. Sci. Gulf Caril,., 4: 1-94. Acknowledgements 1955. A summer study I am grateful to Dr. Clark Hubbs of the Sf ^^e biology and ecolooy of East Bay, ,, . .° , „ , , . , . Texas. Texas .Jour. Sci., 7: 316-343, 430- University of lexas for advice and assistance 453 during this study. My sincere thanks are ex- 1956. Ecological investi- tended to the Directors and the Board of gations in a disturbed Texas coastal es- Trustees of the Rob and Bessie Welder tuary. Ibid., 8: 296-327. Wildlife Foundation for a grant which 1957. Biologic and hy- helped make this study possible. drographic adjustment in a disturbed f -111 f. T 1 T wrn 1 ^uli coast estuary. Limnol. and Ocean- 1 am indebted to Bobby ). wilks and ogr., 2: 198-212. numerous other graduate students of the Renfro, William C. 1959. Survival and University of Texas for their assistance in migration of fresh-water fishes in salt collecting fishes. water. Texas .Jour. Sci., 11: 172-180. Appreciation is extended to Dr. J. H. Simmons, Ernest G. 1957. An ecological Kutkuhn, U.S. Bureau of Commercial" Fish- ^^^^'^'^^ °^ ,^^^ "PP^, L^guna Madre of J T^ wr TVT Tk* T- 1 J T ■ Texas. Puhl. Inst. May. Set., 4(2): 156- enes, and Dr. Wm. N. McFarland, Institute 2CO. of Marine Science, University of Texas for Simpson, Don G. and Gordon Gunter 1956. suggestions and critical review of the manu- Notes on habitats, systematic characters script and life histories of Texas salt water References Cited cyprinodonts. Tulane Stud. Zool., 4: 115- ^1,'nf^^''!wT5^•^^TTS^?S-?'^F''7 ^r^"' Springer, Victor G. and Kenneth D. and C. LAVETT Smith 19o4. Fishes from Woodburn 1960. An ecological study of the Escambia River, Alabama and Flor- ^^^^ ^-^^^^^ ^^ ^^^ ^^^^^ g| ^.^ Ida, with ecoiogic and taxonomic notes. o^ pi ^'^^,o Z3...w d„,. e„,.' 1 . 1 in,< D, 1 7 \T r e ■ n; -7 it\r inn ^n^ •->*• ^"- ^ons., t^roj . Fan. ber., 1 1-104. Proc. Acad. .\at. Scu Plula., 106: 109-164. > . / Chipman, Robert K. 1959. Studies on the a tolerance of certain freshwater fishes to ABSTRACT brine water from oil wells. Ecology, Fishes were collected at three sta- 40(2): 299-302. tions on the Aransas River, a non- Gunter, Gordon 1945. Studies on marine flowing, normally brackish body of fishes of Texas. Publ. Inst. Mai: Sci., water on the Central Texas Gulf Coast. 1(1)- 1-190 A drought prevailing during- the first " _'..-. 1950. Distributions and ^alf of the study produced a highly abundance of fishes on the Aransas Na- f }"^ environment Subsequent ram- tional Wildlife Refuge, with life history ^^" %"^^ .^^7"^ salinities provided an v,^+«^ 77 V7 iio\ oniAi opportunity to note the occurrence of notes. J hid., 1(2) : 89-101. j;- u . i * , .i , ,. iishes taken at three stations over a Herre. Albert W. T. C. 1929. An Ameri- wide range of salinities. Twentv-six can cyprinodcnt m Philippine salt ponds. species are categorized as to their sa- Phdippine .Jour. Sci., 38: 121-127, pis. 1-3. Unity tolerance. Five species of fresh- Hildebrand, Samuel F. and William C. water fishes were found in a salinity Schroeder 1928. The fishes of Chesa- of 17f*/(Mi. Seven species were found to peake Bay. Bull. U. S. Bur. Fish. 43: tolerate salinities ranging from nearly 1-366. fresh to well above 45'V(i(i. TULANE STUDIES IN ZOOLOGY VOLUME 1, 1953-54 Number Price 1 On a new genus and species of mysid from Louisiana (Crustacea, Malacostraca), by Albert H. Banner, pp. 1-8 (June 1, 1953) . .I$0.25 2 A contribution on the life history of the lizard Scincella laterale (Say), by Richard M. Johnson, pp. 9-27 (July g, 1953) 75 3 An outline for the study of a reptile life history, by Fred K. Cagle, pp. 29-52 (July 28, 1953) 75 4 A population of Holbrook's salamander, Euri/cea longicauda guttolineata (Hol- brook), by Robert E. Gordon, pp. 53-60 (August 15, 1953) 25 5 A redescriptlon of the crawfish Proca7n- barua hinei (Ortmann) (Decapoda, Astacl- dae), by George Henry Penn, pp. 61-68 (September 1, 1953) 25 6 A new burrowing crawfish of the genus ProcamJiarus from Louisiana and Missis- sippi (Decapoda, Astacidae), by George Henry Penn, pp. 69-76 (September 15, 1953) 25 7 The life history of the crawfish Orconectea (Faxonella) clypeatus (Hay) (Decapoda, Astacidae), by Elsie Wayne Smith, pp. 77- 96 (October 23, 1953) 50 8 Ostrincola gracilis C. B. Wilson, a parasite of marine pelecypods in Louisiana (Cope- poda, Cyclopoida), by Arthur G. Humes, pp. 97-107 (December 21, 1953) 25 9 Hybrid Invlabillty between Rana pipiena from Wisconsin and Mexico, by B. Peter Volpe, pp. 109-123 (February 8, 1954) 35 10 The butterflies and skippers of Louisiana, by Edward Nelson Lambremont, pp. 125- 164 (April 30, 1954) 60 11 Two new species of the genus Oraptemys, by Fred R. Cagle, pp. 165-186 (August 26, 1954) 75 12 The taxonomic status of the mid-Gulf Coast Amphiuma, by Imogene R. Hill, pp. 189-215 (August 26, 1954) 35 Complete volume, including title page and table of contents, (unbound) $4.25 VOLUME 2, 1954-55 1 A new Eulimnadta from the rice fields of Arkansas with a key to the American species of the genus (Conchostraca, Lim- nadiidae), by N. T. Mattox, pp. 1-10 (Sep- tember 14, 1954) $0.25 2 Studies In the ecology of the narrow- mouthed toad, Microhyla carolinenaia caro- linensia, by Paul K. Anderson, pp. 13-46 (November 8, 1954) 50 3 A new species of Diaptotnus from Louisi- ana and Texas with notes on the subgenus Leptodiaptomua (Copepoda, Calanoida), by Mildred Stratton Wilson, pp. 47-60 (No- vember 29, 1954) 25 4 Three new species and new records of southern milllpeds, by Nell B. Causey, pp. 61-68 (December 28, 1954) 25 5 Notropia baileyi, a new cyprlnld fish from Pascagoula and Mobile Bay drainages of Mississippi and Alabama, by Royal D. Suttkus and Edward C. Raney, pp. 69-86 (January 12, 1955) 30 VOLUME 2, 1954-55-Continued Number Price 6 A reconsideration of the racer. Coluber constrictor, in eastern United States, by Walter Auffenberg, pp. 87-155 (February 25, 1955) 1.00 7 Notropia hypailepis, a new cyprinid fish from the Apalachicola River system of Georgia and Alabama, by Royal D. Suttkus and Edward C. Raney, pp. 157-170 (Feb- ruary 25, 1955) 30 8 The fishes of two Gulf Coastal marsh areas of Florida, by John D. Kilby, pp. 171-247 (May 4, 1955) 1.00 Complete volume, including title page, table of contents and index (unbound) ... .$3.75 VOLUME 3, 1955-56 1 Notropia asperifrona, a new cyprlnld fish from the Mobile Bay drainage of Alabama and Georgia, with studies of related spe- cies, by Royal D. Suttkus and Edward C. Raney, pp. 1-33 (July 8, 1955) |$0.50 2 A new Louisiana copepod related to Diap- tomus {Aglaodiaptomua) clavipea Schacht (Copepoda, Calanoida), by Mildred Strat- ton Wilson, pp. 35-47 (August 1, 1955) ... .30 3 A new species of Sternotherua with a dis- cussion of the Sternotherua carinatua com- plex (Chelonia, Kinosternidae), by Don- ald W. Tinkle and Robert G. Webb, pp. 51-67 (August 30, 1955) 50 4 A new Cambarus of the Diogenes section from North Louisiana (Decapoda, Astaci- dae), by George Henry Penn, pp. 71-81 (September 30, 1955) 25 5 Notropia euryzonus, a new cyprinid fish from the Chattahoochee River system of Georgia and Alabama, by Royal D. Suttkus, pp. 83-100 (December 28, 1955) 50 6 Factors Influencing the rate of oxygen con- Bumption of the dwarf crawfish, Camba- rellua shufeldtii (Decapoda Astacidae), by Milton Flngerman, pp. 101-116 (December 18, 1955) 35 7 Identification and geographical variation of the cyprinodont fishes Fundulua oliv 'Z '" ^ SO o « « M o d to- ~l 1 1 1 1 1 1 — 1 1 1 1 \ I I I I 1 1 1 1 1 I I I I I i I I I I I 1 — I 1 1 1 1 1 1 1 1 1 — I 1 1 1 1 1 1 1 1 J f M A M J J A SONOJ f M A M J 1 A SONDJ f ft A M 1 1 A SONDJ f M A U J I A SONOJ f M A 1954 1957 '951 195 9 1940 Monthi and Y»ari Figure 5. Climatic data in relation to reproductive activity in female cotton rats. Data on average monthly temperature and total monthly precipitation are taken from the U. S. Weather Bureau records from Burrvi^ood, La. Reproductive activity in females is based on live and dead samples combined. maximum number of litters produced by the average female is five or six. A female may produce far less than the maximum number of litters when subjected to inclement weath- er or food shortage as, for example, the six- month non-breeding period during the winter of 1957-58. F. Litter Size Most of the data on litter size have been obtained by counting embryos of pregnant femal'rs in dead samples. Additional rec- ords were obtained from pregnant animals captured alive and brought to the laboratory where they gave birth. The mean number of embryos of 20 adult females collected from 1957 to 1959 is 4.8. Ten of these counts were recorded from July to November 1957. The mean for this group is 3.7, with a range from 2 to 5. The remain- ing ten embryo counts were recorded dur- ing the period May 1958 to June 1959. The mean for this sample is 6.0, with a range of 4 to 7. This difference in average litter size occurred during contrasting phases of population growth. The low litter size data from 1957 were obtained during a period of high density. The other sample, however, was collected after the population had de- clined and had begun to increase from a very low density. The difference in the means of these two samples is highly significant at the 0.01 level (Table 2). G. Ovarian Activity In eleven pairs of ovaries from reproduc- tively active adults taken in 1957, the mean number of corpora lutea per pair was 4.5 (range 3-8). Nine pairs of ovaries from adults taken in 1958-59 bad a mean corpora Table 2. Comparison of embryo counts in adult Oryzomys 1957-1959 Sample N d.f. Mean Value Sums of Squares 1957 1958-59 10 10 9 9 3.7 6.0 145 370 t = 3.776 t .01, 18 d.f. = 2.552 No. 4 Neg//s et al: Ecology of the rice rat 105 Sample Table 3. Comparison of ovarian activity in adult Oryzomys 1957-1959 N d.f. Mean Value Sums of Squares 1957 1958-59 11 9 10 8 4.5 7.6 245 576 = 2.22 .05. 18 d.f. 1.734 lutea count of 7.6 (range 4-12) per pair. The difference was significant at the .05 level (Table 3). This trend coincides with similar differences in embryo counts from the two periods. Apparently rice rat litter sizes are directly related to the number of ova released. Litter size in the rice rat may be controlled largely by the activity of the ovaries rather than by resorption rates, im- plantation failure, etc. Estrogen secretion and' the associated gonadotrophins of the anterior pituitary ( FSH and LH ) probably control the number of ova released and thus the litter size. Ovaries examined during nonbreeding periods were considerably reduced in size and lacked maturing follicles. In some fe- males that were reproductively active only one ovary, usually the right, was functional. \ I Figure 6. Photomicrograph showing the corpora lutea of the active right ovary of an adult pregnant Oryzomys. Figure 7. Photomicrograph showing the relatively inactive left ovary of an adult pregnant Oryzomys. the other being greatly reduced in size with no follicular development ( figs. 6,1) . Even when both ovaries were functional, the right often showed greater activity on the basis of corpora lutea and albicantia counts. Fifty- six percent of the corpora were found in the right ovary in contrast to forty-four per- cent in the left. Corpora lutea of pregnancy averaged 1.1 mm in diameter while corpora albicantia averaged 0.5 mm. Atretic follicles were com- monly observed in specimens taken in fall and winter. 106 Tidane Studies in Zoology Vol. 8 H. Growth Rates Nearly always the age of a mammal is difficult to determine. More information on the close relationship of age with physio- logical processes and behavior may lend greater insight into the problems of popu- lation ecology. Growth rate data have been recorded from a total of 49 known-age rice rats in the laboratory. Animals were examined at week- ly and bi-weekly intervals. At each exami- nation, the following data were collected: weight, total length, tail length, hind foot length, ear length, pelage stage, and repro- ductive data. Developmental changes in be- havior were also observed. The growth rate curves in weight and in total length ( fig. 8) are constructed on the basis of several hundred observations of a large sample of animals. An enlightening aspect of these data is that rice rats continue to grow sub- stantially for a considerable period of time, perhaps throughout the average lifetime of an individual. Our known-age data do not extend beyond 270 days of age. However, the measurements of several individuals re- captured in the field that were at least a year old, were considerably larger than our oldest laboratory animals. For example, a subadult male originally captured in October 1957, was recaptured for the last time 20 months later in June 1959. At final capture the animal measured 262 mm in total length, which is considerably larger than the size attained at one year (fig. 8). This extended growth period may well account for the variation in size noted in taxonomic series by some workers (Goldman, 1918; Paradiso, I960). We were anxious to compare the growth rates in the field with those of laboratory- reared rats. Accordingly, eighteen young rice rats born of Breton Island females, were toe-clipped and released on the island in June 1959. Only one of these individuals was subsequently recaptured. We have re- cently gained further information on field growth rates from animals marked as juve- niles and subsequently recaptured. One such animal was marked and recaptured on the same dates that a known-age animal was released and recaptured respectively. These data agree well with our laboratory growth rates ( fig. 8). Once adult status has been attained, body weight per se is not an adequate criterion for age. The variation in weight of those animals 150 days of age and older may be attributed to fat accumulation, reproductive activity, and other factors. Increases in total length, however, seem to show less variation, even at older ages. If age increments of one or two months are assigned, the reliability of aging from growth curves seems to be high. I. Age Composition Evaluation of age composition of live and dead samples was based on the following criteria: weights, total length, reproductive condition, and pelage stages. Comparisons were also made with data collected from known-age animals in the laboratory. None of these criteria was used exclusively or ab- solutely, but was evaluated along with other characteristics. Total length was, by far, the best criterion for age determination. Pelage condition and degree of development of re- productive organs facilitated age determi- nation of juvenile and subadult groups. A sharp division between subadult and adult groups was difficult to define. An in- termediate group, (subadult-adult) was thus established. Approximate measurement cri- teria for separating age groups were as follows: Juvenile — TL up to 210 mm, wt. up to 32 gms. Subadult — TL 205-220 mm, wt. 30- 50 gms. Subadult-adult — TL 220-230 mm, wt. 50-55 gms. Adult — TL 230+ mm, wt. 55 gms and over. The age composition of rice rats at various periods from 1957-1959 are indicated in figure 9- The trends in composition reflect closely the changes observed in reproductive activity and density. J. Behavior Our trapping procedure revealed that rice rats are active only at night. We have ob- served neither activity nor trapped rats dur- ing daylight hours even though traps were left set throughout each 24-hour period. Greater activity on cloudy and rainy nights was indicated by higher trap success. Blair (1951) noted that Peroniysciis polionotus No. 4 Negus et al: Ecology of the rice rat 107 o o K o o CO — t— ® ® o o Q. o o E ? O O o CO O O CM O 00 O o ■o UI ui u I m 6 u 9-\ 1 -u 'O 1 -c-l CS c CO _C ^ "m 3 0) J2 .r^ CO C8 en 0) CO C3 VI D -u ^ 0) o (U a3 o ffi QJ ^ c3 hii T3 3 ^ 0) -^ ?H c« a 0) '3 cS C3 4-» .a* o 0) «tH ^ "5 bJO >» C3 V3 ^ -M 0* o '3 su +-> J^ a, c c3 •^^ O CO 0) 03 OS £* CO < a> -t-> C J=j= OJ >. -t-> •«.j s ?-t c Ol o — !h -u "rt 3 BS-O S CO a> CS 3 ^H rt c o 'S SS j-t rt 'S 2 j-» T3 +J 0) "o o -u w^ c tn «« o 01 -a 0) a; 0) > ^ 0) •jj O 00 CO "O c OJ 0) . CO 0) H-S en >> r— 1 •1— > T3 '3 +J c O T3 2. C3 I* c-o CO cS CO T3 <4H C CO c o en a; o o; g "? c3 'rt CO CO a> o & ca S _c 3 3 ^ .5f -M ^■^ V CO > 3 o =4H 'A u c3 o > o "5 0) o o I—" 3 00 o 2 (U ca 0) -a 4-» >» 3 c fc J5 lO -u 3 a ^ c3 O" 108 Tulane Studies in Zoology Vol. 8 A 81 s J s A 4 4 4 A 42 J S SA n 36 11 Jo /y - Aug. , 1957 N -. 23 Ocf. - Dec. , /957 N : 89 A A 23 68 J 38 S 34 S A 5 J 3 s 1) SA 18 Ja n . - Mar . , \9 58 May - Aug . , 1958 N -- 77 N -- 38 A 41 J S S A 14 24 21 A 43 J S SA 22 19 15 Feb . - Mar . , I 959 N = 58 June , 1959 N z 58 A 67 s SA E 27 Dec. , 1959 N = 33 P^igure U. A^e composition of some Oryzomys samples from Breton Island. The letters in blocks represent age classes, juveniles: J; subadults: S; subadult-adults: SA; adults: A. Numbers in block represent percentage of respective age categories in each sample. The abundance of young animals in the Jan. - Mar. 1958, sample may be a reflection of stunted growth as a consequence of the severe winter. No. 4 Negus et al: Ecology of the rice rat 109 on Santa Rosa Island, Florida were much cinereus, Blarina hrevicauda, Peromyscus more active on cloudy nights than on moon- leucopus and maniculatus and Clethrionomys lit nights. gapperi. He further commented: "All of We conducted systematic searches for nest these species occupy, at the same time, the sites in the sedge community. A number of stratum where this fungus grows, and it ap- nests were found, usually located on high pears to be a food of more than passing ground either in a hollow log or under pieces importance to the several species." At least of driftwood. Nests that housed a single rat two different types of fungi from the family were rather elongate structures, about 2-3 Endogonaceae were recognized, Endogone inches wide and 5-6 inches long, of loosely and an unidentified genus. The occurrence interwoven grass. One nest was located at of sand with this fungus in the stomachs is the base of a thick clump of sedges. During probably a result of Endogone's subter- winter several large oval nests about 6 inches ranean habit. Plant parts too well chewed in diameter were found under boards. One fo permit identification made up a large of these contained five large rice rats; two portion of the contents. Stem and leaf parts other nests contained four and three indi- and unidentified seeds of numerous plant viduals. Such communal nests were observed species were abundant. Flower parts oc- only during winter. curred in eieht different samples. Insects of One instance of homing was recorded, ^^rio^s types were frequently encountered. Eight animals were released 250 feet east ^^^ stomach of one rat collected in Decem- and west of the trapsite in November 1957. ^^^ ^^^'^ eleven larvae. Two moths, a butter- One juvenile male returned from the west' ^^y' ^°"^^ lepidopteran scales, spiders and He was then released 250 feet east of home ''iq'-iatic insects, a centipede and the chitinous and returned the following night. On the P^''" °^ '^^"^ unrecognized insects were third night, he was released 250 feet north found among the arthropod portions of the of home, and failed to return. contents. Six rice rat stomachs contained Although we did not see evidence around '^^^" 'f ^" ^^"^'' ^^'^''^f ^^"^^^^ c""^^^- nest sites of food cachmg, a considerable '"'"'^ '^L' greatest bulk of the insect re- quantity and variety of seeds was found T'"""- ^he size of two snail radulae taken under one of the bunks when rice rats in- ^'""^ ^ specimen collected in February sug- vaded the cabin in the winter of 1959-60 ^^'^^ ^^""^ ^^^ '^^^^ ^'^^ ^^^ certainly over This was the only time that the cabin was ^^''^ '?'^^"' indicating that rice rats some- invaded and was coincident with high popu- ''"'^' ^"'^^^ ^^°"^ '^'^ beach. Another stom- lations. During the same period oil com- ''^^ ^ ^ specimen collected in the same pany employees on North Breton reported '^°'''^\^°T!'! scales of a small an abundance of rice rats around their gar- ^''•\ ^ ^''^-'^j'^ structure probably from a bage area mollusk, was found in a July sample. By following tracks of Oryzomys in the L. Adrenal Gland Weights sand in winter, we observed considerable Adrenal glands were removed and weighed digging around the bases of grass and sedge f.^m all animals collected for dead samples. clumps, presumably in search of food. ^o compare adrenal weights from rats of K. Food Habits varying sizes, we converted each pair to c- , . .1 milligrams of adrenal weight per gram of Sixty-one stomach contents were exammed ,,-, ^ r.j i from various seasons to determine food ^"^^ ^J'^^^.- ^ ^""^"J'^^^y ^^J'' ^^ habits (fig. 10). The food eaten through- ^^'^^l ^^^^ '' presented in Table 4. A con- out the year implies an extremely varied siderable increase m adrenal weight occurred diet, thus the difficulty of generalizing about ^'^"^ December 1957 to February 1958, par- any one period of sampling. We were sur- ticularly when compared to adrenal weight prised to find the mycelial threads and "^ August 1957. The increase of adrenal spores of the fungus Endogone in the stom- weight from December to February is achs of November, February, and May sam- greater when expressed as milligrams per pies. Hamilton (1941) mentioned the pres- gram of body weight than when expressed ence of this fungus in several mammals, as gross adrenal weights ( Table 4 ) . Gen- Synaptotnys cooperi, Sorex jumeus, Sorex eral body weight loss throughout the popu- 110 Tulane Studies in Zoology Vol. 8 SfOAj a i u I % S ".' 96oiU9^J9^ 30^ No. 4 Negus et ah Ecology of the rice rat 111 Table 4. Adrenal weights from samples of Oryzomys on Breton Island Mean a drenal Mean wt./gm Mean adrenal Mean adrenal body wts. body wt. wts. mgm/gm Date wts., mgm Range gms 9 $ 9 and $ N Aug. 1957 6.0 3.8- 8.0 59.2 .1114 .1114 8 Dec. 1957 8.5 3.9-18.3 39.8 .208 .212 .2047 14 Feb. 1958 14.4 6.4-28.0 43.9 .322 .320 .3208 31 May 1958 15.4 11.5-19.8 60.8 .331 .190 .2905 5 Jul.-Aug. 1958 7.3 3.5-10.8 49.3 .220 .167 .1720 15 Dec. 1959 19.4 11.2-36.0 48.9 .396 .379 .3957 25 lation during the winter accounts for this. There was general decline of adrenal weight in 1958. At this time populations were recovering from very low density. We do not have adrenal data for the winter of 1958. However, a sample of 25 pairs of adrenals from December 1959, indicates that weights had again increased substantial- ly ( fig. 11). These high weights, as in 1957-58, accompanied fairly high densities as well as bad weather conditions. V. Discussion The causes of population fluctuations have been variously attributed to a number of en- vironmental phenomena. Climatic changes, inter- and intra-specific competition, dis- ease, the availability and nutritive value of food are but a few. Pitelka ( 1958 ) divided theories of population cycles into two schools of thought: (1) those which contend a close relationship between population changes and extrinsic variables, and (2) those 40- 30- o c ai 20 TJ -o « 10' Dec. , 1959 Jan. - Feb., 1958 Dec, 1957 o a. 20 B 30 Y W t 40 i n 50 60 gms Figure 11. Distribution an _ samples, showing relationship ous sizes and ages. id regression lines of rice rat adrenal weights from ip of adrenal weights to body weights in animals of 70 three vari- 112 Ti/lane Studies in Zoology Vol. 8 which emphasize an intrinsic mechanism. increase in adrenal size. He attributed this In one of the early studies of population increase and the attendant changes in repro- cycles, Hamilton ( 1937 ) suspected murine ductive activity to socio-psychological stress epizootics as a primary causative agent in inducecl by high density. First, we must reducing mouse populations. consider the magnitudes of densities actually Lemmings on the arctic tundra have been involved in the experiments. Sixteen mice studied by Pitelka (1957), who pictured per square foot area approximates 697,000 an inseparable trio of biotic interaction: mice per acre by extrapolating the upper lemmings, soil, and vegetation, "Winter limit of density at which increased adrenal cuttings of vegetation and the resulting re- weights were still manifest. Densities of 32 moval of food and cover expose peak den- mice per cage are equivalent to 1,394,000 sities of lemmings to predation, which is mice per acre. Caged densities at which the usual agent figuring in the inevitable adrenal hypertrophy occurred, in apparent decline of the population." Frank (1957) direct response to density, were obviously agreed with Christian's (1950) earliest hy- many times the maximum densities encoun- pothesis though differed on one essen- tered even in natural plague populations, tial point. Frank attributed the intrusion One of the densest populations on record is of harsh frost periods accounting for the described by Hall (1927) who estimated abruptness of the decline as the ultimate 82,280 animals per acre in a California trigger eliciting the crash of vole popula- plague of house mice and voles. Densities tions. Such climatic importance is closely of Christian's 42 square foot cage ( 17,000 allied to our concept of rice rat population per acre) are far above the usual peak fluctuations. numbers encountered in rodent populations. Chitty (I960) suggested another theory. Bodenheimer (1957) studied Microtus He believed that some self-regulating mech- gnentheri for five years and found, contrary anism has evolved in voles. Under special to other caged studies, that in a series of ten, circumstances this mechanism makes them two square meter cages these mice "took to more susceptible to mortality factors by a each other very well." "In the few cages deterioration in the quality of the popu- where fighting led to a few killings, its lation. occurrence was independent to the intial Five instances of high populations coinci- vole number." He concluded that the inten- dent with the flowering of bamboo in South sity of fighting is as much dependent upon America and Malagasy Republic ( Madagas- individual sociability as upon environmental car) are discussed by Grasse (1955). Ta- factors. "Periods of heavy killing were not naka ( 1956, 1957) reported that bamboo preceded by periods of unrest in the cages." flowering does not always coincide with Three to six months often separated periods vole peaks in Japan. of fighting. If we are to properly evaluate the pro- Chitty (I960) remarked, "contrary, there- posed intrinsic mechanisms influencing pop- fore, to what some authors appear to believe, ulations, we must first be fully cognizant useful results will not necessarily follow of the assumptions and experimental data from keeping animals at a density several that have formed the basis for such theories. hundred times that occurring in nature, and The adreno-pituitary exhaustion theory pro- at the same time failing to provide a sub- posed by Christian ( 1950, 1956a, 1956b, stitute for their runways and cover." An- 1959a, 1959b) has gained greater accept- other factor that defies evaluation and yet ance and popularity than any other recent must certainly exert its effect upon caged work on intrinsic factors. mice is the confinement of the cage itself Christian's theory is based in part upon which forces contact among the occupants; the premise that he effectively isolated den- ^ condition that is certainly never approached sity as the single variable responsible for m the field. changes in adrenal cortical activity, repro- Under such high density and confinement, duction, and other physiological processes in if social stress is an important mechanism caged populations. In house mouse popu- in population dynamics, one would expect lations varying in density from one to 16 the most drastic responses to manifest them- mice per square foot, he found a progressive selves by changes in reproduction, mortality, No. 4 Negus et al: Ecology of the rice rat 113 and health via the adreno-pituitary system. How does the magnitude of response in the laboratory compare with that of the field.-' In natural populations, confinement is lack- ing, densities are lower, and there is less assurance of contact. Thus the adrenal re- sponse to social stress in Christian's caged populations should be greatly magnified. Such, however, is not the case. The maxi- mum amount of increase in adrenal weights in Christian's mice with increasing density is actually small (25%), partiailarly when compared with the magnitude of adrenal weight increase (95%) that accompanies merely the onset of reproductive activity in female cotton rats ( Table 6 ) . Christian supported his theory through the interpretation of his caged animal data on Mus (1955, 1956a), wild Baltimore Rutins (Christian and Davis, 1955, 1956), natural populations of Microtus (Adams, Bell and Moore, unpublished. Christian, 1959b), and evidence from Louch (1956, 1958) and Green, et al (1938, 1939). Green's work was recently found deficient in its support of the adreno-pituitary hy- pothesis (Chitty, 1959). Louch (1958) studied two populations, one at Mudd Lake and another at Hammers- ley Marsh. He stated that two factors brought about the greater adreno-cortical activity observed in the fall of 1952 in both areas. One of these, the drought conditions of that fall, appeared to act in both areas to bring about increased adreno-cortical ac- tivity. The other factor, high population density, was present only in the Mudd Lake area and appeared to increase the adreno- cortical activity of the mice to significantly higher levels than at Hammersley Marsh. Louch suggested that the drought conditions and the high population density present in the Mudd Lake area may have had an ac- cumulative effect resulting in significantly higher adrenal weights and lower eosinophil counts than in the area where drought alone was a factor. Thus Louch presented data in which density may be isolated, in terms of adrenal weight, from climatic impact, under natural conditions. We shall therefore compare Louch's con- fined population with his two wild popula- tions and use the adrenal weights under con- fined conditions as a yardstick for social pressure due to density. Louch offered the following information on adrenal weights in cages (6' x 25') and in the wild popu- lations (Table 5). Let us assume that 0.149 mg/gm of body weight (the mean adrenal weight of Ham- mersley and Mudd Lake populations at low density) represents a basic unstressed adre- nal weight for Microtus. The mean differ- ence between the basic adrenal weight (0.149) and the mean Hammersley adre- nal weight under drought conditions (0.194) is 0.045. This value (0.045) thus repre- sents the increased weight of the adrenals due to drought. In the same way 0.081 rep- resents the mean adrenal weight increase due to drought and density at Mudd Lake (0.230 — 0.149 = 0.081). We arrive at the density value of 0.036 (0.081—0.045 = 0.036) if Louch's interpretation of the data is accepted, i.e.., that the Hammersley popu- lation was varied by drought only (since Table 5. Adreyjal iveight data frorn caged and natural populations of Microtiis pennsylv aniens (Louch, 19.56, 1958) Pop. end point Pen All animals killed Approx. high population Mean adrenal wt. S (mgm/gm body wt.) Diff. of mean adrenal wts. among cages (mgm/gm body wt.) A 15 B 42 C 20 28 53 67 .104 .144 .086 .04 (B) .06 (C) -.02 (A) Period Nov.-Dec. 1952 Feb.-Nov. 1953 Mean ad. wts. Hammersley (drought (mgm/gm body wt 0.194 0.152 Mean ad. wts. only) Mudd Lake (drought & density) .) (mgm gm body wt.) 0.230 0.145 114 Tulane Studies in Zoology Vol. 8 density was low) and that the Mudd Lake eluded that differences in nutrition find population was affected by drought and their expression in differences in fertility, density. These data preclude the necessity of postu- The value (0.045) which we have at- iating an indirect relationship between the tributed to drought is thus equal to the adre- environment and the animal, nal weight difference (0.04) between the Christian (1959a) defended his hypothe- highest density (Pen B) and the lowest sis on the basis of a commonly held assump- ( Pen A) (Table 5). These data raise the tion that some single factor common to all question: why attribute the causes of adre- populations underlies the causes of fluctu- nal enlargement to social stress when climate ations. He clearly stated a common pathway alone seems to play so great a role? which he has chosen on the basis of his field Still another comparison may be made, and laboratory data: "socio-psychological The mean adrenal weight (0.145) of the factors are the principal stimuli for the adre- Mudd Lake population at low density, in nal and reproductive responses as these are the absence of drought, is equal to the mean factors common to all populations." Is adrenal weight (0.144) of the highest cage socio-psychological stress the only factor densities ( Pen B). Thus where density is common to all populations? non-contributing, the high adrenal weight Both nutritional and climatic factors are under natural conditions is presumably a equally common to all animal populations, response to the environment. Wild populations are constantly responding Christian (1959b) stated: "There must to environmental vicissitudes. Logically we be a maximum amount of space that would assume that the more significant stresses still permit the mice to interact. . . ." One upon the population will be generated di- might logically conclude that space may be rectly from the environment with social con- sufficiently unlimited to render social inter- tacts and relative density at low levels as action ineffective in natural populations. compared with caged conditions. Christian (1959a) recognized the import The limited distribution and abundance of of environmental vicissitudes by establish- food plants on Breton Island, the unsheltered ing his "unit of social pressure". He con- nature of the sedge community, and the sidered it to be a variable unit from one severe wind and wave action, coupled with population to the next, depending upon the a water table just beneath the surface of the existing enviromental conditions as well as sand, all contribute to the sub-optimal na- the density. The unit of social pressure is rure of the habitat. Despite the highly om- thus defined as the net effect of favorable nivorous food habits of Oryzo?nys. plant or unfavorable extrinsic factors mediated food when abundant becomes predominant through the common pathway of social stress in the diet. Conversely, during the winter, among the individuals. Thus, the "unit" is stomachs contained largely insects and fungi placed upon a sliding scale dependent not ( Endogonaceae ) and few vegetative parts. upon density per se, but upon environmental As the numbers of rice rats rise in re- conditions, sponse to favorable climate and abundance Environmental factors are admittedly of of food, competition for nest sites becomes great importance. Is Christian justified, progressively acute. Suitable sites on the however, in mediating all such factors island are limited largely to logs and debris through the common pathway of social located on high ground and to clumps of stress? Christian himself (1959a) recog- vegetation beyond the reach of high water, nized the significance of work by Srebnik, The impact of marginal environment com- Nelson, and Simpson (1958) regarding the bined with the hazards of winter may im- direct effect of protein deficiency on the pose considerable stress on the population, reduction of circulating gonadotrophins. Falling temperatures lead to greater nutri- Dale (1955) presented evidence that cal- five needs in the face of depleted food re- cium intake may have a direct effect upon serves. The population is likely to suffer ovulatory rates and viability of eggs in heavy losses with the onset of a severe pheasants. Bodenheimer ( 1949) did a series winter, the attendant food shortages and de- of experiments with Microtus. He used a lay of spring growth, variety of grain and mixed feeds, and con- In December 1957, impending disaster No. 4 Negus et al: Ecology of the rice rat 115 to the population was manifested by the low average weight in a sample of 62 animals. The emaciated condition of 75 rats was visibly evident in January - February 1958. Most of the animals examined during this sampling period are described in the field notes as being thin and "bony" and pelage in poor condition. The mean weight loss for the entire sample compared to the December 1957 collection was 10.6 grams (fig. 4). Poor physical condition thus pre- vailed throughout the population just prior to the sharp decline in early 1958. The magnitude of adrenal weight increase in our Oryzomys population (based on milli- grams per gram of body weight) is of the order of 200 per cent from low to even mod- erate densities (7-10 per acre). One is tempted to conclude that the effect of social interaction on adrenal weight changes are overshadowed by other environmental ef- fects in the light of subtle adrenal weight changes (25%) observed in extreme cage densities as compared with those of much lower densities found in nature. At what point then, does high adreno-cortical ac- tivity precipitate a measurable response in the population.^ The concept that adrenal weight serves as a yardstick for the causes of population fluctuation has received great emphasis. However, in our review of the literature we have been impressed by the inconsistencies of the data. For example, Mullen (I960) in a presentation of aberrant adrenal weight data from a natural popu- lation questions the reliability of adrenal en- largement as a criterion of population den- sity "stress". The rise and fall of the Oryzomys popu- lation on Breton Island and the coincident change in adrenal weights can clearly be interpreted in the light of Christian's theory of socio-psychological stress. But is there not an equally valid hypothesis on the basis of our data? We can just as well explain the increase in adrenal size and complete cessa- tion of reproduction, as well as weight loss in the population, on the basis of climate and food. The winter of 1957-58 was one of great severity and duration in Louisiana. The highest adrenal weights occurred in late winter and early spring. Depleted food sup- plies coupled with low temperatures im- posed an unusually severe stress upon the population. One has only to postulate that the late initiation of vegetative growth in the spring, coupled with prolonged inclem- ent weather, presented a condition of poor nutrition and low temperature. These con- ditions directly affected the reproductive physiology and health of the population. Our interpretations of the interrelationships between environmental factors and popula- tion density is presented in figure 12. Our forementioned conclusion is further substantiated by data collected at the same time for Sigmodon populations on the main- land of Louisiana and Texas. During the period 1957-58, populations of Sigmodon in southern Louisiana study plots of 5 acres each were at low to moderate densities (3-6/ acre) in oldfield habitats. In this form as well as other small mammal species of the mainland, all reproduction ceased for an extended period from November 1957 to May 1958, the identical period of non- reproductive activity expressed by our is- land population of Oryzomys. A sample of 20 adrenal pairs from a cot- ton rat population at low density in Lou- isiana during July-August 1958, had a mean weight of 18.7 mgms (Table 6). On the other hand, a sample of 32 adrenal pairs from a plague population (several hundred per acre, Davis, 1958) of cotton rats in Texas during January 1959, had a mean weight of 12.6 mgms. This same popula- tion was sampled in March 1959. At this time 51 pairs of adrenals had a mean weight of 18.1 mgms. Reproductive activity in this population began in late April 1959, and a sample taken in May yielded 100 per cent pregnant females. Thirteen pairs of adre- nals from this same sample had a mean weight of 27.5 mgms. However, the weights of female adrenals in this sample were much higher ( x = 39.8 mgms) than those of males ( x =: 1 6.9 mgms ) . The foregoing data imply that density and contact are not necessarily important factors influencing adrenal weight changes in natural populations. It is difficult to imagine greater stress due to density and contact in a natural population than that which was present at peak densities in the Texas plague. At night in a short walk through the plague infested area, one could witness hundreds of cotton rats scurrying about. Often three or four animals were seen huddled together in the mouth of a burrow, 116 Tulane Studies in Zoology Vol. 8 z 3 o UJ Q 5s o N ^ 5> ^^ 5*. $ o O 73 ^ m c I o 1 -M 1 0) ff ^ PQ / 0) +-> a t:: « CO (V 0) ^ ft U CO M oJ ^^ . «s » fe^ No. 4 Negus et ah Ecology of the rice rat 117 Table 6. Adrenal weights of Sigmodon hispidiis Texas, Texas, Texas, Louisiana, Jan. 1959 March 1959 May 1959 June-July 1958 (high density) (high density) (low density) (low density) N = 32 N = 51 N = 13 N = 20 Mean combined 12.5 18.1 27.47 18.7 adrenal 9 = 12.4 9 =20.25 9 =39.8 9 =22.1 weights $ = 12.6 i =16.03 $ = 16.9 $ = 15.4 (mgms) Mean mgms 0.136 0.224 0.213 0.234 adrenal wt/ 9 =0.156 9 =0.236 9 =0.320 9 =0.311 gm body $ =0.123 $ =0.193 $ =0.121 i =0.179 weight Mean body 81.8 80.8 133.6* 80.0 wt. gms * high mean weight is in part caused by pregnant females. or feeding side by side along fencerows. Virtually every standing piece of herbaceous vegetation had been consumed and cover was non-existent. Even in such conditions of density and lack of cover, all animals ap- peared to be in excellent condition, and with the coming of the spring, all females examined were pregnant with an average embryo count of 7.0. Although Sigmodon is a very different animal from Oryzomys, adrenal responses to high density and the attendant effects should be manifest in both forms. If such comparative data is not in agreement one should look for other factors that may ac- count for the rise and fall of populations. Rather than postulating an indirect effect of climate and food upon the populations through social stress, we postulate a direct response of the populations to environ- mental vicissitudes via their reproductive physiology. This, in fact, seems more rea- sonable, in view of the general response of all rodents during the winter of 1957-58. We emphasize that social stress is not the only factor that may account for adreno- cortical hypertrophy. We can say with as- surance that mammals may become stressed by means entirely independent of social stress, i.e. starvation, temperature, etc. The response of the individual to the impact of these extrinsic variables is direct, based on experimental data now available (Dale, 1955; Ershoff, 1952; Selye, 1946). In fact, direct response to climate and food offers a more plausible explanation of some popu- lations prospering at extremely high den- sities (Kalela 1949, Bodenheimer 1957, Elton 1942) than does the concept of social stress. The adreno-pituitary hypothesis states that, "the growth of mammalian populations is controlled by a sociopsychological -physio- logical feed-back system that responds to changes in population density." (Christian, 1959b). We find this hypothesis difficult to accept as an explanation for our obser- vations of Oryzomys and as a general state- ment about all mammals because of the fol- lowing questionable aspects of the concept. 1. Christian's experiments dealing with crowded m,ice in small cages served to simu- late an isolated factor, density, ivhich pre- sumably affects the rise and fall of natural populations. The data of Crowcroft and Rowe (1957, 1958) cast doubt upon the utility of labora- tory findings on crowded mice. They found significant infant mortality resulting from the observer's disturbance. Infant mortality has been one of the limiting factors in caged studies (Christian, 1956a). Pen size and nest box design also contributed to limitation of population growth. "Deaths of unweaned mice are more likely to be caused by intraspecific strife when the nest boxes are small, with a single opening than when they are large with a 'through passage"." "If such mechanisms of population control are so dependent upon specific experimental conditions, we must question their impor- tance in free living populations." Some of Christian's experiments involved densities approaching one million per acre and more 118 Tulane Studies tn Zoology Vol. 8 — a magnitude never realized in nature. season, weights of adrenals clearly differed Hall (1927) recorded the highest density at between the sexes and depended on the 82,280 per acre in a plague of house mice reproductive condition of the animals. Re- and voles in California. Clarke ( 1955) failed productive activity resulted in small male to produce a decline in numbers in outdoor adrenals and large female adrenals and the enclosures despite overcrowding, and yet opposite situation existed in nonactive in- intraspecific strife was certainly limiting dividuals. Pregnant females did not have their increase. larger adrenals than those which exhibited 2. The social stress theory has been ap- other conditions of sexual activity. Mc- plied to all small mammal populations and Keever suggested that "stress through mal- clearly requires some dependence upon den- nutrition would result m a significant in- sity. It assumes that social interaction in- crease in adrenal size in males, but a de- creases with density. crease of even greater proportions in the Pearson (I960) studied a population of adrenal size of females." Microtus 7nontanus as it increased 5 to 10 Southwick (1958) was unable to detect fold. The amount of photographically re- changes in reproduction, mortality, fecun- corded activity in the runways and thus the ^ify. or adrenal weights related to increasing social contact remained constant. Our studies density of house mice in English corn of this same species in Wyoming corrobo- ricks, although 45 f? of the adult males rate Pearson's observations. showed signs of severe fighting. Southwick In the summer of I960, following a sharp ^nd Bland ( 1959) repeated Christian's ex- decline in small mammal populations, we Penments with caged mice of a different found single pairs of adult Microtus mon- strain. They failed to detect changes in tanus living in widely separated lush clumps ^^^^^^^ ^^ights due to crowding, of bluegrass (Poa). These animals had ob- Our Sigmodon adrenal weight data (Table viously overwintered. As their numbers in- 6) agree well with McKeever's observations, creased through the breeding season, the Male weights decreased with onset of re- young of several generations remained in the productive activity, while female adrenals immediate area of the parents, but the net- gained considerably in weight with increased work of runways increased with density, reproductive activity. Louch (1958) also This colonial hab-t of Microtus families and observed that reproductively active female the expansion of runway systems in the Microtus pennsylvanicus had larger adrenals colony suggest to us that social contact does, than males. in fact, remain quite constant. Presumably, Thus in Microtus montanus, Microtus as densities continue to rise, the colonial pennsylvanicus, Sigmodon hispidus and Ory- runway .systems would continue to expand zomys palustris the change in adrenal weight into the extensive uninhabited parts of the appears to be at least as much a reflection surrounding habitat. Social contact, however of reproductive influences as an index to a would remain constant, as shown by Pear- "sociopsychological- physiological feed-back son's data. Admittedly, densities and the system". Certainly both factors need to be network of runways may ultimately increase taken into account. If more were known to levels which cause increased social con- about the age composition and the repro- tact. Many populations, however, decline ductive condition of Christian and Davis' when densities are far below those required Baltimore rat studies, an explanation might to occupy all available habitat. be forthcoming for the high male adrenal 3. Adrenal weight increase is a reflection weights and low female adrenal weiglits in of stress induced by increasing density or the low stationary population. environmental factors mediated through the 4. During peak populations fecundity single pathivay of social interaction. drops as a result of increased social strife. McKeever (1959) found no significant Hamilton (1937) de.scribed high fecun- differcnces between mean adrenal weights dity in the fall during a peak population and of Microtus montanus from two high and a drop in the proportion of pregnancies dur- five low density populations when animals ing the winter. Reproductive failure might of the same sex and reproductive condition more reasonably be attributed to the stress were compared. During the reproductive of cold weather. No. 4 Negus et al: Ecology of the rice rat 119 Crowcroft and Rowe (1958) pointed out that "lowered fecundity in response to high numbers has not been found in any naturally occurring house mouse population." 5. Nutrition and other environmental variables play a subordinate role to social stress and are simply fed into the "feedback system" through the single pathway, social stress. Quality of food has been virtually ignored in most of the work directed at demon- strating the importance of density dependent factors. Poole's studies (I960) of the European hare, Oryctolagus, in Australia, substantiated Siivonen's (1957) suggestion that food qual- ity may be of major importance in influenc- ing fecundity, and thus population growth. Poole found that reproduction is a direct reflection of seasonal conditions, the onset of breeding being determined primarily by the occurrence of a flush of new pasture growth "in those years and areas where the 'autumn break', with its sudden amelioration of conditions, ( rain followed by new pasture growth) is well defined, the autumn repro- duction- may have a sharp onset and reach a peak of density comparable with the spring activity." Poole recorded 7 percent of the females pregnant in August preceded by 18 months of drought with but 0.80 inches of rain in July and 0.22 inches in the first two weeks of August. The pasture was dry. Further rain in September improved the pasture con- siderably and incidence of pregnancies rose to 78 percent. October rains were sparse, 0.03 inches, and the pregnancies dropped to 47 percent. Rains from mid October to the third week in November further increased pasture growth, and by November 15, 85 percent of the females were pregnant. Tem- peratures increased from a monthly maxi- mum mean of 61 °F in October to 79°F in December and about 80 °F until February 1955. By early January 1955, pregnancies dropped to 9 percent. Siivonen compared the peaks and troughs of a small herbivorous mammal ( voles ) and tetraonid populations over a 25-year period and found that they closely coincide. The low years were all preceded by late springs and the highs preceded by favorable springs, with respect to green plant food. Andersen (1952) found that the numbers of hares in Denmark rose and fell coincident with early and late spring over a 30-year period. Siivonen noted that the "condition of the female during pregnancy and the suck- ling period of the first litter is reflected in the succeeding litters. If the first litter is not belated and if it is a success, this litter will usually be capable of reproduction dur- ing the same reproductive season." "The reproductive rate of the snowshoe hare in pens of Evo Game Research Station would seem to support this assumption. In years when the early spring plants have been largely delayed, the litters have in general remained small and their number per female has often been reduced to one only." By considering the severe spring of 1957, sever- est compared with the previous 12 years "as regards green plants," Siivonen was able to predict the decrease year in the caper- caillie. The 1958 Sigmodon plague that we ob- served in Texas was preceded by two springs of high rainfall and luxuriant plant growth, following a 7-year drought. Similar climatic circumstances led up to the plague popula- tions of Microtus montanus in northwestern United States in 1958 (Vertrees, 1959). The highest crude protein, carbohydrate, and mineral contents in grasses occur in the young actively growing stage and the level of these substances decreases with maturity. Rainfall leads to an increase in these nutri- ents (French, 1959). Another important constituent of pasture grasses and other species is the plant estro- gens. At least five types of estrogens are contained in over 50 species of plants repre- senting numerous families (Andrews, 1958; Bradbury and White, 1954). At least three of the species are known to be preferred foods of certain mice; alfalfa in Microtus ochrogaster (Jameson, 1947) and Foa in Microtus montanus ( Unpublished ) . Jameson (1947) demonstrated the prefer- ence of Microtus for alfalfa (73 percent of cuttings in runways) where it constituted but 25 percent of the vegetation. During the 1957-58 plague of Microtus which swept the northwestern United States, the mice severely damaged red clover, alfalfa, pota- toes, wild cherry, and wild plum, all of which contain estrogens. The estrogenic ac- tivity in alfalfa has great variability as to season, stage of maturity, time of year, lo- 120 Tulane Studies in Zoology Vol. 8 cation of stand and the variety of alfalfa The average home range size of males was ( Bickoff, 1959). High levels of estrogen somewhat larger than that of females, are particularly evident however during early The extent and time of the breeding sea- spring growth (Bullough, 1955). The levels son was variable. The rats ceased breeding also vary from one year to another (Bickoff, in November, 1957, and did not begin again et al, 1960). Assay methods for the activity until the following May. Conversely, in 1958 of plant estrogens demonstrate an increase breeding continued through the summer, in uterine weight, and ovulation may be in- f^n^ and winter, and into the spring and duced in hares by injecting an extract of summer of 1959. The average number of embryos per fe- The proximity of the primary consumers male in 1957 was 3-7, while for 1958-59 it (herbivorous species) to the primary pro- ^as 6.0. The mean embryo count for all ducers (green plants) would manifest great females was 4.8. On the basis of ovarian changes in reproduction if slight nutritional analysis, litter size appears to be influenced changes in the green food occurred. Our primarily by the number of ova released, most drastically fluctuating animals (micro- Trappmg records indicate the average tme rodents, hares, and tetraonids) are longevity of rice rats on Breton Island to be primarily dependent upon plant food whose ^^^^^ -j nionths. A few individuals live nutritional levels are probably related to longer than one year, climatic changes. , , , , . ., /^ I , 1 f A growth curve based primarily upon In light of our present knowledge of nu- ^^^^ ^^^^ 49 known-age rice rats in the tritional changes in rodent plant foods (pro- laboratory is presented. Apparently Ory- teins, carbohydrates, minerals, and estro- ^ ^^^^, continuously for at least one gens), a sharp change in the quality of ^j^j^,^ -^ ]„^^,^^ ^,^^^ ^^^^ individuals green plants could have immediate effects ^^^ j^ ^i^^j^ j^^^^,^^, ^^^^-^^^^ j^ales and fe- on the reproductive potential and eventual ^^^^^^ become sexually mature at 40-45 days influence on the rise or fall of the popu- ^f ^g^ -p^^^l ^^^^^^ j^ ^ ,^ore reliable cri- lation. terion of age than weight or other standard Our model for population dynamics of external measurements. Oryzomys \t^^^s nutritional factors in a ^j^^^^i ^^-^^^^^ ^^^j^j ^,-^^^ j^^^j^y ^^j questionable state. Our data are presently ^^^^^^ ^hey were highest during severe lacking in this regard. Nevertheless, if as ^-^^^^^ ^^^^^h^ ^^^^^ populations were reia- we suppose plant nutrient levels are closely ^^^^i j^^^^^ ,^^^ 1^^^,^ j^,i 3^n,„,^r related to climatic events, then the popula- ^^^^^^ regardless of density. tion changes of Oryzomys on Breton Island t- 1 , 1 • r • 1 • 1 i j^ „ , ° , 1- ^ ,• ■ , I Food habits or rice rats on the island do not contradict a chmatic-nutritional hy- ... ^^ , • , • , t Dothesis were variable. Food consisted mainly 01 seeds and vegetation during the growing sea- VI. NUMMARY 5on; insects and fungus lEndogone) became A rice rat population was studied for 3 important items at other seasons, years on Breton Island, Louisiana. The rat Considerable weight loss throughout the population was limited primarily to a Fim- population occurred in the harsh winter of bristylis community on the south side of the 195708, suggesting that food shortage may island. have been acute. Decreases in density seemed to be closely The impact of climatic factors with a related to severity and duration of winter, changing food supply and the unsheltered Densities were quite high in summer and nature of the habitat may have exerted a fall of 1957, declined sharply in late winter decisive influence on reproduction and of 1957-58, recovered gradually through the mortality. summer, fall, and winter of 1958, and into The concept of a density -dependent socio- the summer of 1959. Another sharp decline psychological - physiological feed-back sys- occurred early in I960. The winters of 1957 tern as a basic mechanism regulating growth and 1959 were unusually severe. of mammal populations is questioned in Home ranges for many adult animals re- light of our investigations and those of mained relatively stable for some months. other authors. jvjo. 4 Negus et al: Ecology of the rice rat 111 VII Acknowledgements factor of plant juice. Amer. Jour. Physi- , , . r oL, 142: 487-493. We wish to acknowledge the assistance ot br^dbury, R. B. and D. E. White 1954. Robert C. Feuer, Austin T. Fitzjarrell, Wil- Estrogens and related substances in Ham C. Mobberly, and C. Robert Shoop both plants. Vitamins and Hormones, 12: 207- in the field and in the laboratory. Appre- 233. ciation is also extended to Professor Joseph Brimley, C. S. 1923 Breeding dates of . „ r , . J • ■ J .fi^o^:^^ r^( small mammals at Raleigh, Morth Caro- A. Ewan for his aid in identification of j^^^ ./ortr. Mamma/., 4: 263-264. flowering plants; Dr. Donald E. Stone tor bullough, William S. 1955. Hormones and collection and identification of flowering mitotic activity. Vitami)is und Hormones, plants; Dr. Arthur L Welden for the iden- 13: 261-292. tification of the fungi of the family Endo- Chitty, Dennis 1959. A note en shock dis- gonaceae; and, to Margaret Jane Negus for ease. Ecology, 40: 728-731. preparation of figures and" typing of the 1960 Population proces- ^ ^ . ° jr o g^g ^^ ^Y^Q vole and their relevance to gen- manuscript. ^^.^1 theory. Canad. Jour. Zool., 38: 99- 113. VIII. References Cited Christian, John J. 1950. The adreno-pitu- American Ornithologists' Union 1957. itary system and population cycles in Checklist of North American Birds (5th mammals. Joiir. Mammal, 31: 247-259. ed.), American Ornithologist:;' Union, 691 1955. Effect of popula- pp. tion size on the adrenal glands and repro- Andersen, Johs 1952. Fluctuations in the ductive organs of male mice in popula- field hare population in Denmark com- tions of fjxed size. Amer. .Jour. Physiol., pared with certain climatic factors. Rii- 182: 292-300. statieteellisid Julkaisuja (Papers on Game 1956a. Adrenal and re- Research), 8: 41-43. productive responses to population size in Andrews, Frederick 1958. The estrogenic mice from freely growing- populations, activity of alfalfa and other forages. Ecology, 37: 258-273. Fcedstuffs, Feb. 1, pp. 34a-35a. 1956b. The relationship Barbehenn, Kile R. 1955. A field study between adrenal weight and population of growth in Microtus pennsylv aniens. status of urban Norway rats. Jour. Mam- Jour. Mammal, 36: 533-543. mal, 37: 475-486. BiCKOFF, E. M. 1959. The chemistry and 1959a. Control of popu- distribution of estrogens in forages. 6th lation growth in rodents by interplay be- Technical Alfalfa Conference. U.S.D.A., tween population density and endocrine Agric. Res. Sew., ARS-74-15. physiology. Wddl Diseases, 1: 1-36. A N Booth A L Liv- 1959b. The roles of endo- "" i'NGST0N7"and A. P. Hendrickson 'i960. crine and behavioral factors in the growth Observations on the effect of drying on of mammalian populations. In: Compan,- estrogenic activity of alfalfa samples of i^ve Endocrinology, Wiley, N. Y., pp. 71- varying maturity. Jour. A.nim. Sci., 19: "'• 745-753. and David E. Davis 1955. Blair, W. Frank 1940. Home ranges and Reduction of adrenal weight in rodents populations of the meadow vole in south- by reducing population size. Trans. No. ern Michigan. Jour. Wildl Mgt., 4: 149- ^"^^^- ^^ ^l Cont., 20: 1//-189. 161 1956. The relationship „....._ 1951. Population struc- between adrenal weight and population 'lure, social behavior, and environmental status of urban Norway rats. -/o^rr. Mam- relations in a natural population of the mal., dr. 4^o-4»b. beach mouse (Peroniyscus polionotus leu- Clarke, J. R. 1955. Influence of numbers cocephalus). Contr. Lab. Vert. Biol, on reproduction and survival in two ex- Univ. Mich., i8: l-iT. perimental vole populations. Proc. Roy. 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The Mammals of North America. Ronald Press Co., N. Y., 1083 pp. Hamilton, W. J., Jr. 1937. The biology of microtine cycles. Jour. Agric. Res., 54: 779-790. 1941. The food of small forest mammals in eastern United States. Jonr. Mammal., 22: 250-263. - 1946. Habits of the swamp rice rat Oryzomys palnstris jjalustris (Harlan). Amer. Alidl. Nat., 36: 730-736. Harris, Van T. 1953. Ecological relation- ships of meadow voles and rice rats in tidal marshes. Jour. Mammal., 34: 479- 487. Hayne, Don W. 1949. Two methods of es- timating population from trapping rec- ords. Ibid., 30: 399-411. Jameson, E. W., Jr. 1947. Natural history of the prairie vole (mammalian genus Microtus). Univ. Kan. Publ, Mus. Nat. Hist., 1(17) : 125-151. Kalela, Olavi 1949. tJber Fjeldlemming- invasionen und andere iri'egulare Tier- wanderungen, mit einer Ubersicht der Kleinnagergradationen in Finnisch-Lapp- land 1900-1948. Zool. Soc, Zool. Bot. Fennicac "Vanamo", 13(5): 1-190. Lloyd, Francis E. and S. M. Tracy 1901. The insular flora of Mississippi and Lou- isiana. Dull. Torrey Bot. Club, 28: 61- 101. Louch, Charles D. 1956. Adrenocortical activity in relation to the density and dynamics of three confined populations of Microtus pennsylvanicus. Ecology, 37: 701-713. 1958. Adrenocortical ac- tivity in two meadow vole populations. Jour. Mammal., 39: 109-116. McKeever, Sturgis 1959. Effects of repro- ductive activity on the weight of adrenal glands in Miootus mo))ta}ius. A}iat. Rec, 135: 1-5. Mullen, David A. 1960. Adrenal weight changes in Microtus. Jour. Manunal., 41: 129-130. Odum, Eugene P. 1955. An eleven year his- tory of a Sig)nodo)i population. Ibid., 36: 368-378. Paradiso, John L. 1960. Size variation in the rice rat. Ibid., 41: 516-517. Pearson, Oliver P. 1960. Habits of Mi- crotus califo)'nicus revealed by automatic photographic records. Ecol. Monogr., 30: 231-249. Pitelka, Frank A. 1957. Some character- istics of microtine cycles in the Arctic. Arctic Biology, pp. 73-88, Oregon St. Coll. Corvallis, Ore. 1958. Some aspects of population structure in the short-term cycle of the brown lemming in noithern Alaska. Cold Spring Harbor Symposia on Quant. Biol., 22: 237-251. Poole, W. E. 1960. Breeding of the wild rabbit, Oryctolagus (uoiiculus (L) in I'e- lation to the environment. C.S.I.R.O., Wildl. Res., 5(1) : 21-43. Russell, R. J. 1936. Physiography of lower Mississippi River Delta and reports on No. 4 Negus et ah Ecology of the rice rat 12- the geology of Plaquemines and St. Ber- nard Parish. La. Dept. Cons., Geol. Bull., No. 8: 1-454. Schmidt, Karl P. 1953. A Check List of North American AniphibiuJis a)!(l Rep- tiles. Amer. Soc. Ichthyologists and Her- petologists, 280 pp. Selye, Hans 1946. The general adaptation syndrome and the diseases of adaptation. Jour. Clinical Endocrin., 6: 117-230. SiivoNEN, Lauri 1957. The problems of the short-teim fluctuations in numbers of tetraonids in Europe. Snome)i Riista)iho- ito; Riistatieteellisia Jiilkaisuja (Papers on Game Research; Finnish Game Foun- dation), 19: 1-44. Small, John K. 1933. Manual of the Sonth- eastern Flora. Publ. by author, N. Y., 1554 pp. SouTHWiCK, Charles H. 1958. Population characteristics of house mice living in English corn ricks: density relationships. Proc. Zool. Soc. London, 131: 163-175. and V. P. Bland 1959. Effect of population density on adrenal glands and reproductive organs of CFW mice. Amer. .Jour. Physiol., 197: 111-114. Srebnik, Herbert H., M. M. Nelson, and M. E. Simpson 1958. Response to exo- genous gonadotrophins in absence of die- tary protein. Proc. Soc. Expt. Biol. Med., 99: 57-61. Stickel, Lucille F. 1948. The trap line as a measure of small mammal populations. Jour. Wildl. Mgt., 12: 153-161. Svihla, Arthur 1931. Life history of the Texas rice rat (Oryzomys palustris texen- sis). Jour. Mammal, 12: 238-242. Tanaka, Ryo 1956. Fluctuation in vole pop- ulations following the widespread synchro- nous flowering of bamboo grasses on Mt. Turugi. Bull. I\ochi Womoi's College, 4: 61-68. 1957. An ecological re- view of small mammal outbreaks with special reference to their association with the flowering of bamboo grasses. Bidl. Kochi Women's Univ., Ser. Nat. Sci., 5: 20-30. Vertrees, J. D. 1959. Economic control as- pects. In: The Oregon Meadow Mouse Irruption of 19.57-1958. Ore. State Coll., Corvallis, Ore. Abstract A three year study of the rice rat, Oryzomys palustris, on Breton Island, Louisiana, is reported. Information is recorded on population density changes, home ranges, reproduction, food habits, growth, adrenal weights, and behavior. Climatic and nutritional factors are considered of great importance in regu- lating population growth. The adreno- pituitary hypothesis of Christian is dis- cussed in light of these and other data. TULANE STUDIES IN ZOOLOGY VOLUME 1, 1953-54 Number Price 1 On a new genus and species of mysid from Louisiana (Crustacea, Malacostraca), by Albert H. Banner, pp. 1-8 (June 1, 1953) . .I$0.25 2 A contribution on ttie life history of the lizard Scincella laterale (Say), by Richard M. Johnson, pp. 9-27 (July 3, 1953) 75 3 An outline for the study of a reptile life history, by Fred R. Cagle, pp. 29-52 (July 28, 1953) 75 4 A population of Holbrook's salamander, Eurycea longicauda guttolineata (Hol- brook), by Robert E. Gordon, pp. 53-60 (August 15, 1953) 25 5 A redescriptlon of the crawfish Procam- barus hinei (Ortmann) (Decapoda, Astaci- dae), by George Henry Penn, pp. 61-68 (September 1, 1953) 25 6 A new burrowing crawfish of the genus Procambarus from Louisiana and Missis- sippi (Decapoda, Astacidae), by George Henry Penn, pp. 69-76 (September 15, 1953) 25 7 The life history of the crawfish Orconectea (Faxonella) clypeatus (Hay) (Decapoda, Astacidae), by Elsie Wayne Smith, pp. 77- 96 (October 23, 1953) 50 8 Ostrincola gracilis C. B. Wilson, a parasite of marine pelecypods in Louisiana (Cope- poda, Cyclopoida), by Arthur G. Humes, pp. 97-107 (December 21, 1953) 25 9 Hybrid Inviabillty between Rana pipiens from Wisconsin and Mexico, by H. Peter Volpe, pp. 109-123 (February 8, 1954) 35 10 The butterflies and skippers of Louisiana, by Edward Nelson Lambremont, pp. 125- 164 (April 30, 1954) 60 11 Two new species of the genus Oraptemys, by Fred R. Cagle, pp. 165-186 (August 26, 1954) 75 12 The taxonomic status of the mid-Gulf Coast Amphiutna, by Imogene R. Hill, pp. 189-215 (August 26, 1954) 35 Complete volume, including title page and table of contents, (unbound) $4.25 VOLUME 2, 1954-55 1 A new Eulimnadia from the rice fields of Arkansas with a key to the American species of the genus (Conchostraca, Lim- nadiidae), by N. T. Mattox, pp. 1-10 (Sep- tember 14, 1954) $0.25 2 Studies in the ecology of the narrow- mouthed toad, Microhyla carolinensia caro- linensia, by Paul K. Anderson, pp. 13-46 (November 8. 1954) 50 3 A new species of Diaptomus from Louisi- ana and Texas with notes on the subgenus Leptodiaptomus (Copepoda, Calanoida), by Mildred Stratton Wilson, pp. 47-60 (No- vember 29, 1954) 25 4 Three new species and new records of southern miUlpeds, by Nell B. Causey, pp. 61-68 (December 28, 1954) 25 6 Notropis baileyi, a new cyprlnid fish from Pascagoula and Mobile Bay drainages of Mississippi and Alabama, by Royal D. Suttkus and Edward C. Raney, pp. 69-86 (January 12. 1955) 30 VOLUME 2, 1954-55-Continued Number Price 6 A reconsideration of the racer. Coluber constrictor, in eastern United States, by Walter Auffenberg, pp. 87-155 (February 25. 1955) 1.00 7 Notropis hypsilepis, a new cyprlnid fish from the Apalachicola River system of Georgia and Alabama, by Royal D. Suttkus and Edward C. Raney, pp. 157-170 (Feb- ruary 25, 1955) 30 8 The fishes of two Gulf Coastal marsh areas of Florida, by John D. Kilby, pp. 171-247 (May 4, 1955) 1.00 Complete volume, including title page, table of contents and index (unbound) ... .$3.75 VOLUME 3, 1955-56 1 Notropis asperifrona, a new cyprlnid fish from the Mobile Bay drainage of Alabama and Georgia, with studies of related spe- cies, by Royal D. Suttkus and Edward C. Raney, pp. 1-33 (July 8, 1955) $0.50 2 A new Louisiana copepod related to Diap- tomus (Aglaodiaptomus) claripes Schacht (Copepoda, Calanoida), by Mildred Strat- ton Wilson, pp. 35-47 (August 1, 1955) ... .30 3 A new species of Sternotherus with a dis- cussion of the Sternotherus carinatus com- plex (Chelonia, Kinosternldae), by Don- ald W. Tinkle and Robert G. Webb, pp. 51-67 (August 30, 1955) 50 4 A new Cambarus of the Diogenes section from North Louisiana (Decapoda, Astaci- dae), by George Henry Penn, pp. 71-81 (September 30, 1955) 25 5 Notropis euryzonus, a new cyprlnid fish from the Chattahoochee River system of Georgia and Alabama, bv Roval D. Suttkus. pp. 83-100 (December 28. 1955) 50 6 Factors Influencing the rate of oxygen con- sumption of the dwarf crawfish. Camba- rellus shufeldtii (Decapoda Astacidae), by Milton Flngerman, pp. 101-116 (December 88,1955) 35 7 Identification and geographical variation of the cyprinodout fishes Fundulua olivO' ecus (Storer) and Fundulua notatua (Rafl- nesque), by Jerram L. Brown, pp. 117-134, (February 3, 1956) 50 8 The physiology of the melanophores of the Isopod Idothea exotica, by Milton Flnger- man. pp. 137-148 (April 12, 1956) 30 9 Osmotic behavior and bleeding of the oyster Crassostrea virginica, by Milton Fln- german and Laurence D. Fairbanks, pp. 149-168 (April 12, 1956) 50 10 Anatomy of the eyestalk of the white shrimp, Penaeus setiferua (Linn 1758), by Joseph H. Young, pp. 169-190 (June 22. 1956) 50 Complete volume. Including title page, ta- ble of contents and Index (unbound) $4.00 VOLUME 4, 1956 1 A study of the distribution and taxonomy of the percid fish Percina nigrofaaciata (Agassiz), by Ronald W. Crawford, pp. 1- 55 (August 1. 1956) $0 76 TULANE STUDIES IN ZOOLOGY VOLUME 4, 1956-Continued Number Price 2 Experimental Fi hybrids between Bufo valliceps and Bufo foxvleri, by E. Peter Voipe, pp. 59-75 (September 30, 1956) 40 3 Ad outline for the study of an amphibian life history, by Fred R. Cagle, pp. 77-110 (October 31, 1956) 40 4 Notes on habitats, systematic characters and life histories of Texas salt water Cyp- rlnodontes, by Don G. Simpson and Gordon Gunter. pp. 113-134 (December 31, 1956) .35 5 Domlnance-subordinance relationships In the crawfish Cambarellus ahufeldtii, by Mildred Eileen Lowe, pp. 137-170 (Decem- ber 31, 1956) 45 6 Propogatlon of the white shrimp, Penaeua aetiferua (Linn.) In captivity, by Malcolm C. Johnson and J. R. Fielding, pp. 173-190 (December 31, 1956) 30 Complete volume, including title page, ta- ble of contents and Index (unbound) $2.50 VOLUME 6, 1958 Number Price 1 The systematics and ecology of the Sterno- thaerus carinatua complex (Testudinata, Chelydrldae), by Donald W. Tinkle, pp. 1-56 (March 31, 1958) $1.25 2 The butterflies of Mississippi, by Bryant Mather and Katharine Mather, pp. 61-109 (June 6, 1958) 1.00 3 Aquatic and semlaquatlc Hemlptera of Mis- sissippi, by Clifton A. Wilson, pp. 113-170 (September 5, 1958) 1.00 4 The copepod genus Halicyclopa in North America, with description of a new species from Lalse Pontchartrain, Louisiana, and the Texas coast, by Mildred Stratton Wil- son, pp. 176-189 (December 31, 1958). Ontogeny of the first and second pleopoda of the male crawfish Orconectea clypeatua (Hay) (Decapoda, Astacldae), by Joe B. Black, pp. 19(3 203 (December 31, 1958) ... .60 Complete volume, including title page, table of contents and Index (unbound) $3.50 VOLUME 5, 1957 1 Oumbusia heterochir, a new poecUild fish from Texas, with an account of Its hybrid- ization with O. affinis, by Clark Hubbs, pp. 1-16 (March 18, 1957) I$0.30 2 Nt'w calanohl copepods of Pontella Dana and Labidocera Lubbock with notes on the dlstrHnition of the genera in the Gulf of Mexico, by Abraham Flemlnger, pp. 17-34 (March 18, 1957) 30 3 Three new crayfishes from Alabama and Mississippi (Decapoda: Astacidae), by Hwrton U. Ilobbs, Jr. and Margaret Wal- ton, pp. 37 52 (March 18, 1957) 30 4 Heat death and associated weight loss of the oyster Craaaostrea virginica, by Milton Flngerman and Laurence D. Fairbanks, pp. 53-62 (April 1, 1957) 30 6 The Odonata of Louisiana, by George II. Ulck, pp. 69-135 (May 15, 1957) 1.00 6 Endocrine control of the red and white chromatophores of the dwarf crawfish, Cambardlua shujeldti, by Milton Finger- man, pp. 137-148 (June 7, 1957) 30 7 Hormones coutroUing the chromatophores of the dwarf crawfish, Cambarellua ahu- feldti ■ their secretion, stability, and sepa- ration by filter paper electrophoresis, by Milton Flngerman and Mildred B. Lowe, pp. 149-171 (June 7, 1957) 40 8 Cyprlnld fishes of the subgenus Cyprinella of Xotropia. III. Variation and subspecies of Notropis venuKtua (Girard), by Robert II. Glbbs, Jr. pp. 173-203 (August 7, 1957) .50 9 The earlv development of Rana capita aevo- aa, by E. Peter Volpe, pp. 205-225 (Septem- ber 12. 1957) 35 11 The skeleton shrimps (Crustacea : Caprel- lldae) of the Gulf of Mexico, by Joan E. Steinberg and Ellsworth C. Dougherty, pp. 265-288 (December 30, 1957) 40 10 Variation and subspecies of the crawfish Orconectea palmeri (Faxon) ( Decapoda, Astacldae), by George Henry Penn, pp. 229-262 (September 12, 1957) 60 12 The systematic status of the suckers of the genus Moxoxtoma from Texas, New Mexico, and Mexico, by C. Richard Robins and Edward C. Raney, pp. 289-318 (Decem- ber 30. 1957) 45 Complete volume. Including title page, ta- ble of contents and index (unbound) ....$5.00 VOLUME 7, 1959 1 An Illustrated key to the crawfishes of Louisiana with a summary of their distri- bution within the State (Decapoda, Asta- cldae), by George Henry Penn, pp. 3-20 (April 23, 1959). Comparison of the chromatophorotroplns of two crayfishes with special reference to electrophoretic behavior, by Milton Finger- man, pp. 21-30 (April 23, 1959) $0.60 2 A review of the seabasses of the genus Centropristea (Serranidae), by Rudolph J. Miller, pp. 33-68 (July 9, 1959) 0.75 3 Digenetic trematodes of marine fishes from the Gulf of Panama and Blminl, British West Indies, by Franklin Sogandares-Ber- nal, pp. 69 117 (August 24, 1959) 1.00 4 Parasites of the commercial shrimps, Pen- aeua aztecua Ives, P. duorarum Burkenroad, and P. aetiferua (Linnaeus), by Dwayne Nathaniel Kruse, pp. 123-144 (October 19, 1959). The larva of the oak toad, Bufo quercicua Holbrook, by E. Peter Volpe and James L. Doble, pp. 145-152 (October 19, 1959) 60 Complete volume, including title page, table of contents and index (unbound) .... $2.65 VOLUME 8, 1960 1 Studies on the backswimmers of Costa Rica (Hemiptera; Notonectidae), by John L. De Abate, pp. 1-28 (April 29, 1960) $0.60 2 Three Ascocotyle complex trematodes (Het- erophyidae) encysted in fishes from Louisi- ana, including the description of a new genus, by Franklin Sogandares-Bernal and John F. Bridgman, pp. 31-39 (October 28, 1960). Age and growth of the spot, Leiostomua wunthurua Lac6p6de, by Bangalore I. Sun- dararaj, pp. 41-62 (October 28, 1900) 0.65 Orders should be addressed to Meade Natural History Library, c/o Department of Zoology, Tulane University, New Orleans, 18, La., USA Pli>ase make remUtance payable to "Tulane UniTersitj" flllL^ 0 JUN131961 HARVARD IVERSITY Volume 8, Number 5 May 31, 1961 A QUANTITATIVE STUDY OF THE MOVEMENT OF PARAMECIUM CAUDATUM AND P, MULTIMICRONUCLEATUM D. F. SEARS, DEPARTMENT OF PHYSIOLOQY, and LILA ELVEBACK, DEPARTMENT OF BI08TATI8TIC8, SCHOOL OF MEDICINE, TULANE UNIVERSITY, NEW ORLEANS, LA. NINE DIGENETIC TREMATODES OF MARINE FISHES FROM THE ATLANTIC COAST OF PANAMA FRANKLIN SOGANDARES-BERNAL and LUCY McALISTER SOGANDARES, DEPARTMENT OF ZOOLOGY, TULANE UNIVERSITY, NEW ORLEANS, LOUISIANA TULANE UNIVERSITY NEW ORLEANS TULANE STUDIES IN ZOOLOGY is devoted primarily to the zoology of the waters and adjacent land areas of the Gulf of Mexico and the Caribbean Sea. 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Robert Shoop UNASr I 'JUN13196I HAftVARO VNIVERSiry TULANE STUDIES IN ZOOLOGY Volume 8, Number 5 May 31, 1961 CONTENTS A QUANTITATIVE STUDY OF THE MOVEMENT OF PARAMECIUM CAUDATUM AND P. MULTIMICRONUCLEATUM D. F. Sears and Lila Elveback .._- 127 Editorial Committee: Stuart S. Bamforth, Assistant Professor of Zoology, Tulane University, New Or- leans, Louisiana Theodore L. Jahn, Professor of Zoology, University of California, Los Angeles, California Ralph Wichterman, Professor of Biology, Temple University, Philadelphia, Penn- sylvania NINE DIGENETIC TREMATODES OF MARINE FISHES FROM THE ATLANTIC COAST OF PANAMA Franklin Sogandares-Bernal and Lucy McAlister Sogandares 141 Editorial Committee: Harold W. Manter, Professor of Zoology, University of Nebraska, Lincoln, Nebraska Walter E. Martin, Professor of Biology, University of Southern California, Los Angeles, California Satyu Yamaguti, Visiting Parasitologist, United States Agricultural Research Cen- ter, Beltsville, Maryland A QUANTITATIVE STUDY OF THE MOVEMENT OF PARAMECIUM CAUDATUM AND P. MULTIMICRONUCLEATUM ' D. F. SEARS, Department of Physiology, and LILA ELVEBACK, Department of Biostatistics, School of Medicine, Tulane University, New Orleans, La. A previous study of the effect of inert compared with measurements in which the gases on oil-water emulsions suggested a drop contained several paramecia. Data char- mechanism whereby these gases could pro- acterizing the spiral paths were obtained duce narcosis (Sears and Fenn, 1957). Ex- from experiments with P. multimicronucle- tension of this research to a biological sys- atum: these data allowed us to test for a tem was desirable. Reports that narcotics, relationship between speed and shape of e.g., chloral hydrate, affected cilia and hence path. Finally, consideration was given to movement of paramecia (Alverdes, 1922) relative errors of one and two dimensional led us to investigate effects of pressures of measurements of the three dimensional path, inert gases on movement of these organisms. Methods and measurements. — Hanging The theoretical work of Ludwig (1929) and drop preparations of paramecia were used the behavioral studies of Jennings (1923) in most of the work. Pyrex discs were suf- presented factors involved in movement of ficient in size to permit observation of three paramecia. However, to use movement as a drops during an experiment. Paths of free criterion of narcosis, these studies and others swimming paramecia were traced on paper consulted did not yield sufficient quantita- using a camera lucida and timed with a stop tive information in the following aspects: watch. Lengths of these lines were deter- ( 1 ) the three dimensional nature of the mined with a map measurer. The length movement; (2) the basic measurements re- divided by the magnification gave an esti- quired to define the spiral path generated mate of the distance traveled by the para- by the movement; ( 3 ) the most accurate mecium. A value for speed at a particular method for estimating distances traveled; time represents a mean speed determined and, (4) whether measurements of move- from at least five tracings of whatver para- ment of single paramecia or of groups would mecia appeared in the field during the two yield more reproducible data. Only by fur- to three minutes usually required to make ther characterization of paramecia move- the tracings. Measurements were made al- ment was it possible to observe and quanti- ternately on the drops. Mean speed and rate narcotic action. This paper is a study standard deviation were calculated for each of movement designed to supply the neces- of these short periods of time. This pro- sary quantitative information. cedure was used especially for measurements Data on speed were obtained from single with single paramecia. individuals and groups of Paramecium cau- for comparison with these experiments, datum and groups of P. multimicronucle- a chamber as designed by Ferguson (1957) atum under conditions which allowed de- ^as constructed. This stroboscopic dark scription of typical speed, variability in field illumination method was used in ex- speed during short time intervals, and change periments with P. multimicronucle atum. in mean speed over long periods of time. Paramecia paths were photographed and re- Individual differences among paramecia un- suited in streaks on 35 mm film. The nega- der the same experimental conditions were tives were projected with a microfilm reader, explored. Variations in measurements on A typical record for this type illumination single paramecia in a drop of media were is shown as figure 1. Due to the large num- 1 This research was begun with funds supplied by Office of Naval Research Grant #NR-100-281 at the University of Rochester, Department of Physiology. Work with P. multimicroniicleatum was supported by United States Public Health Service Grant #RG- 5713, and carried out at Tulane University. 128 Tulane Studies in Zoology Vol. 8 Figure 1. PhotoRi'aph of paramt'cia paths with strolioscopic daik field iHumiiialioii No. 5 Sears and Elveback: Movement of paramecia 129 130 Tulane Studies in Zoology Vol. 8 bers of measurements, the data were pro- cessed with the IBM 650 computer. - The shape of paramecia paths.. — The shape of a Paramecium path has been described as helical ( Ludwig, 1929). Determination of the three dimensional distance traveled may be derived from the parametric equation for a helix: 2 = a^ X = a cos^ y = asin^ As shown on figure 2, the width of the spiral is 2a, and the progression is assumed to be along the z axis of a Cartesian coordinate system. If Lg represents the distance a Para- mecium travels in three dimensions for one complete rotation, i.e., 6 going from 0 to Iw, then L3 = \/ ( 27ra„ ) - -f 2„- Obviously when a = 0, L3 =r 2. Both z and a are available from sketches of paramecia paths or from photographs. From these two measurements (z, a) the helix can be completely described. Thus the angle of progression ( a ) is given by z tana = da The tangent of this angle is the ratio of the distance along the major axis of the helix to the circumference of the cylinder about which the rotation occurs. The curvature K of the path at every point on the helix is cos^ a a when a is 90°, cos a is 0 and the Para- mecium is swimming in a straight line. Torsion T in terms of a was given by Lud- wig as: sin 2a r = 2a when the torsion is equal to curvature, the length of the spiral z is equal to the cylinder circumference about which the spiral is wound. It has been reported (Walton, 1916, Eb- becke, 1935, and Sears, 1957) that rotation about the longitudinal axis of the organism or the curvature of the path changes under - We are indebted to Mr. Bill Nettleton, Tulane Computer Center, for his assistance in programming i.nd will gladly make this program available to any investigator. various conditions. This was the predomi- nant effect determined for the response of paramecia to high pressures of argon ( Sears, 1957). Errors in the measurement of distance. — As already stated, we can calculate the three dimensional distance, L;^, by measuring the length of the major axis of the helix z and its radius a. Also it is possible to measure the distance L2 with a map measurer fol- lowing along the curve obtained from the tracing or photograph of the path. Finally 2 may be measured with a ruler. In our early experiments we determined the Li; distances and reported these in the majority of cases. Lj measurements give more accurate results than straight line dis- tances and allow easy estimates of rotation (see appendix). The availability of a com- puter made calculations of L3 feasible in our recent experiments. The ratio of mean width to mean length of a spiral for P. multimicro- nucleatum was 0.041. Therefore the error as a proportion of L^ when the distance is estimated by L^ would be about one percent. However, the estimate obtained from z measurements would give a three percent error compared to L^. Determination of speed. — Primarily we sought to describe a pattern of movement of paramecia over time periods. There is possibility for variation in this pattern due to different experimental situations; differ- ences in species, media, temperature, age, or pH. These sources of variation are fairly easily controlled. There are other variations, however, which are not amenable to external control. A simple Paramecium will vary its speed during even short periods of observa- tion. Therefore, it is desirable to report the mean and standard deviation of speed meas- urements for these short intervals of time. There is variation: (1) between speeds of single paramecia in the chamber at the same short time interval but in different drops; (2) in patterns of movement of two differ- ent paramecia over a long time interval; and, (3) variation between experiments (between single paramecia and between groups of paramecia). In an attempt to study external factors which might cause variability in speed, we measured speed of single individ- uals and groups of P. caudatum in tap water, lettuce media, malt media, and in a solution recommended by Chalkley (1930). This No. 5 Sears and Elveback: Movement of paramecia 131 solution contained NaCI (0.1 grams), CaCb (0.006 grams), KCl (0.004 grams), NaHCOy (0.004 grams) in one liter of water. Basic variability. — Figure 3 illustrates ex- perimental data for single individuals of P. caudatum. One paramecium was placed in each of three hanging drops in the chamber. Four short interval sets of measurements were made on each drop. The five measure- 1016- 762- 508- 254- ments made on each paramecium during each short interval are plotted, and we see that during a period of 2 minutes a para- mecium may change its speed by a factor of two, although this is unusual. The extent to which the three paramecia differed in their pattern of speed with time is also illustrated. The set of data available for single P. cau- datum was obtained from experiments in- u C/) T3 Q. CO 1270 1016- 762 508' 254 0 1524- 1270- (016- • • 762- 508- .:\ \. • 254- 1 Qk rT •• r 1 100 200 300 Minutes Figure 3. Variation in speed and mean speed of three single organisms {P. caudatnm) in three different drops observed alternately. The small black dots represent single ob- servations. Circles represent mean speed. (Note: 254 fi/sec = 0.01 inches/sec). 132 Tulane Studies tn Zoology Vol. 8 volving 80 drops each containing a single Paramecium and involved a total of 219 sets of two or three minute intervals, taken from two minutes to 30 hours after the paramecia were placed in the chamber. The vast ma- jority of measurement intervals were during the first 8 hours. Several media were used. Means and standard deviations of the five (or more) measurements made during the short intervals were studied. Speed of single P. caudatum. — Standard deviations were computed for each of 219 two-to-three minute intervals, and differed greatly. Even within subgroups of the same media, temperature, pH, and time, differ- ences corresponding to a factor of ten were observed. Distributions of these short in- terval standard deviations for Chalkley and other media (malt, lettuce, and tap water suspensions of paramecia ) are illustrated in figure 4. Shown also are distributions of short interval standard deviations for drops containing more than a single paramecium. With several paramecia in the drop, stand- ard deviations were only slightly larger than those for measurements made on single or- ganisms. With respect to speed vie asm e- ments little is to he gained by limiting ex- periments to a single organism per drop. Speed of P. caudatum and P. multimicro- nucleatum. — In general, speed of both spe- cies decreases from the beginning of experi- ments but tends to approach equilibrium by the end of the third hour (fig. 5). This equilibration time seems to be characteristic of hanging drop preparations. Ferguson (1957) did not report any such long equi- libration required to attain a mean speed when his chamber is used, and our experi- ments with his chamber bear this out. We suspect that variation in COi: tension of the drop makes equilibration necessary; we are now investigating this possibility. Speeds measured in all experiments on both single or many organisms in a drop were averaged for each 100 minute interval. The time interval extends to 700 minutes. Scattered measurements at more than 2,000 minutes confirm the tendency to an equi- librium speed reached after about 300 min- utes. Initial high mean speeds were fre- quently accompanied by large standard de- viations. The relationship between short interval means and standard deviation was examined graphically. For mean speeds in excess of 900 microns per second the standard devi- ations were, in the large majority of cases, also large. For moderate speeds, typical after three hours (254 to 635 )u, sec), no relation- '*~^^TChalkley "D 4) D O ■o y ll Q. 254- 0 P multimicronucleatum -6 P. caudatum 254/J./sec.=.OI in /sec 0 — 1 — 100 T 200 300 400 500 600 700 800 Time in Minutes Figure 5. Speed of P. caudatum and P. mitltimicronucleatum. Bars through each point indicate standard deviations rather than standard errors of the mean since the great variability in speeds is of fundamental interest. Circles refer to P. caudatum and dots show mean speed for P. multimicronucleatum. ship between short interval mean and stand- ard deviation was detected. Ferguson (1957) reported that thirty measurements are required for computation of a mean average velocity. From our meas- urements we estimate that mean speed of P. caudatum at 500 /^/sec with a standard deviation of 127 jj./ sec. At least 70 speed measurements are required to reduce the error of the mean to three percent, and 625 are required for a one percent error. Thirty measurements lead to nearly 5% error of the mean from these values. This may be another difference in hanging drop prepara- tions and the closed Ferguson chamber. Characteristics of the path of P. multi- micronucleatum.— From photographic trac- ings we were able to measure length z as the distance from one peak to the next, and width a as half the depth of the valley of the track, ( see fig. 1 ) . "We analyzed the length and width of the spiral only for P. multimicronucleatum. There were many paramecia in each drop under observation. Photographic tracings of movement were measured at 173 X magnification. Length and width of one complete spiral turn were studied in relation to corresponding speed. The data covered a wide time interval and several temperatures. The greatest number of measurements were made at 20° C. As many as 10 measurements of the spiral were obtained at each short time interval. Meas- urements of a, z and speed were made on a total of 334 paths. The set of 334 paths studied were first ordered on speed. In studying change in the mean values of a and z with speed, speeds were grouped in intervals of 130 /x sec (0.005 inches/sec). Means are plotted in figure 6. Of the three variables, a, z, and speed, the diameter of the spiral, a, had much the largest relative variability. Part of this effect may be due to the fact that, in relative terms, measurement error in a was larger than in z or in speed. It will be seen from figure 6 that there was little change in average length or width of the spiral over the speed range. If a relationship exists it would be a tendency for z to increase with speed. The relationship of a to z was examined by plotting (a, z) pairs for paths corre- sponding to the 120 lowest speeds (281 to 635 /^/sec) and for the 120 highest speeds (889 to 1651 /i/sec) (fig. 7). In each of the two groups correlation between a and z 134 Tidane Studies in Zoology Vol. 8 I524H o 1016 "6 IN 508H 0- Mean width (a) and length (z) of spiral related to speed 18 61 93 66 28 30 24 14 1 1 1 1 1 — 254 508 762 1016 1270 1524 ( Microns per second along L2 ) 1778 76. 2 H (/) c § 50.8H E • o 254H 0- 254 508 762 1016 1270 ( Microns per second along 1524 L2) 1778 Figure C. Mean width a and length z of the spiral of P. mult iinicronucleat ion related speed. At the top of the figure are the numbers of obseravtions for each speed grouping. was weak but positive. There was some tendency for large values of a and 2 to occur together, and this tendency was stronger at high speeds than low. Sets of measurements made on the same drop during a short period of time were also studied. Short intervals means ( a, z ) were plotted against each other. Again positive, but weak, correlation was observed. The times covered ranged from 5 to 422 minutes after paramecia had been put into the chamber. These times seemed to bear no relation whatever to a or z values. From experiments carried out at 20° C, four short interval sets of measurements made during the first hour after putting paramecia into the chamber were analyzed, and compared with four siiort-interval sets of measurements made after 172 minutes. Coefficients of variation were as follows: No. 5 Sears and Elveback: Movement of paramecia 135 Time (in minutes) 5 7 43 45 172 233 289 388 No. measurements 9 12 6 19 12 10 5 10 Coeff. of Var. z 85 20 12 29 29 37 23 30 a 50 39 41 53 44 69 70 49 speed 47 16 21 27 21 22 21 22 Data presented here were characterized by example at 20° C and 289 minutes after great variability in a and z even in the same paramecia were placed in the chamber five drop during a short period of time. For paths gave the following measurements: Curvature Torsion Speed ifi/sec) z (m) a (/.) a K (m-1) T (m-i) 584 1097 116 56° 0.0026 .0040 279 810 29 77° 0.0017 .0076 610 1128 58 72° 0.0017 .0051 356 1504 116 64° 0.0017 .0034 610 1011 17 84° 0.0059 .0062 2540- « • • 2023- • • • • • « • • • ^ 1524- ..... • •• • • • • • • • •• !•• :- • • • • • •••••••• • ^ 1016- 508- 0- 1 1 a in/i 50.8 1016 152 4 2540- Speeds Between 281 and 635/x/sec 2023- • • • « « • 1524- ... 4. - 1016- 508- * : • • •*. • . • ::»« ••• •• ••• • :<.•..:;. • . • • •«• ... »♦•:.::• •• . .. *. »•• • • • • • 0* ■ T I ■ ■ ■■-! a in /I 508 101.6 152.4 figure 7. Relation between length of spiral z and width of that spiral a. Upper plot of distance related to the ratio of a to z. ]V^ Tulane Studies in Zoology Vol. 8 Since there were many (perhaps 10 to 12) paramecia in each drop studied, we cannot, on the basis of these data, say what part of the variability observed is a reflection of difference between paramecia. We have only begun to study the variability in spiral shapes of single paramecia. An interpretation of the spiral rnove- ment. — A theoretical study of spiral move- ment of ciliates was reported by Ludwig. He stated that two forces are responsible for the spiral path: one, a force which alone would cause the organism to go in a circle; the other, a force which causes the organism to rotate about its longitudinal axis. A canoe, if paddled on one side more strongly than the other, will travel in a circle with the side having the greatest force applied directed outward. Ludwig stated that force exerted by cilia of paramecia on the aboral side nor- mally exceeds that applied by the oral side. This causes the organism to make a basic circle. There is a rotation component to the force which cilia are supplying which causes the organism to rotate about its longitudinal axis. This rotatory movement has been at- tributed to the obHque direction of the cilia beat from left backward, toward the right. The organism, therefore, may start moving in a circle to the right, but due to accom- panying rotation of the organism, the circle changes to be directed upward, then to the left, downward, and finally to the right again. Thus, a spiral results. Ludwig stated that characteristics of the a large value for z and smaller for a). ( 2 ) If the torsion remains constant but the curvature increases, the spiral line be- comes fatter (z would decrease) and the width a would increase until the paramecium makes an angle of 45 with the XY plane (assuming progression along the Z axis). As the angle decreases toward zero, the width of the spiral would then decrease. ( 3 ) Asymmetry in rotatory force com- ponents causes a widening and flattening of the spiral path. Ludwig (1929) and Bullington (1925) attempted to determine whether character- istics of spiral patterns would aid in classi- fication of ciliates. Bullington concluded that among species "speed of swimming is directly related with the number of spiral turns. Increasing the speed increases the length of the spiral". It was this statement and the first rule of Lud wig's which caused us to investigate whether, in order to in- crease their speed, paramecia of the same species alter the spiral paths which they follow. Three values for curvatures given above are constant (0.0017 /i."')- The torsion changes and in this case, in agreement with Ludwig's generalization, the radius, a, varied inversely with the torsion; the length of the spiral increased. The question arises to what extent a single paramecium can produce these changes. The following values were obtained from a single P. midtimicYonitde- atum in a hanging drop: Curvature Torsion Minutes Speed z a a K (m-1) T (m-1) 20 600 1300 38 80° 0.0009 0.0045 20 1000 1850 145 64° 0.0013 0.0027 20 900 1330 72 71° 0.0014 0.0043 20 1500 1965 214 56° 0.0015 0.0022 78 900 1156 58 73° 0.0016 0.0048 157 400 1450 72 73° 0.0013 0.0039 221 700 1127 43 77° 0.0012 0.0051 221 600 1272 72 70° l).0()16 0.0044 392 300 867 101 54° 0.0034 0.0047 spiral are affected by changes in ajrvature ( arising from differences in force applied on the oral and aboral surfaces) and changes in torsion (arising from differences in direc- tion of cilia beat). Consideration of these changes led him to three generalizations: ( 1 ) If the curvature remains constant, increasing torsion (rotation) would result in a steeper and more narrow spiral. (That is, Characteristics of the rotation could be measured from only about a fourth of the piiotograpiis of the patlis. In many cases the Paramecium swam in a straight or nearly straight line. Although rotation about the longitudinal axis occurred, no radius, a, could be measured. Where measurable rotation occurred the curvature remained fairly con- stant. Since curvature is related to the bal- No. 5 Sears and Elveback: Movement of paramecia 137 ance of forces on the oral and aboral sides. we may conclude that this ratio of forces was generally maintained. The torsion indi- cates the variation in direction of the cilia beat. There is a weak relationship obtainable from the extremes of the speeds that indi- cates that the length of the spiral increases with increase in speed. However, the middle speed values do not show any clear evidence for such a relationship. As we have shown, there is much variation in the shape of paths which paramecia fol- low. However, our mean path length and width agree closely with those found by Bullington for P. multimicronucleatum. paths of paramecia is illustrated in the fol- lowing data (25° C). Experiments No. of z measurements z (m) Control (1) Control (2) Added CO2 (1) Added CO2 (2) 403 186 218 82 1607± 51 1543± 30 1688± 94 1673+ 86 Ethyl alcohol 2.58 43 2267+157 Mean z values for P. mtdtimicronncleatum placed in the Ferguson chamber in the cul- ture media differ little (about 3%) between the two experiments. Bubbling 100 percent Reference Mean z Range Mean a Range Bullington, 1925 Our data 1290m 1121m 833-1666/x 402-2540m 46m 143-200m 11.5-162m We also measured the length along L2 cor- CO2 in the media caused no significant responding to a single rotation for P. cau- change. However 2.58 volumes percent ethyl datu7n. The mean length of the spiral path alcohol produced a significant change. This of this species so measured (not calculated amount of alcohol was not lethal to the from 2 and a is 784/x. We did not measure paramecia. widths of paths. Bullington's value for ^om concentrations of CO2 were used: length of the spiral of P. caudatum were ^0%, 50%, 90% and 100% of one atmos- from 900 to 2250 microns. ph^^e. The mean 2 values with added CO2 Results presented are for many different were little different from experiments with paramecia and do not show what happens adding CO2. However, the mean a value to an individual path as a paramecium in- for the experiments with CO2 (300 measure- creases its speed. (See fig. 6) But we ex- ments) was 126 /x compared to 195 ^t where peered that in the study of 334 paths any CO2 was not artificially raised. The lowest decided tendency to change either length or a values were associated with the 90 percent width of spiral with increasing speed would CO2 experiments. With no essential vari- have been discernible. We can only say ation in z this indicates a straightening of that in the hanging drop preparation the the paramecia paths as the concentration of tendency for length of the spiral to increase CO2 increased. We therefore propose the with speed is weak but if a real relationship use of orientation ( the angle a ) to indicate exists it is indeed that both increase together, a positive attraction to the gradient of a Again there was a difference in the values chemical, obtained depending upon the nature of the Experimental design. — Relating this in- preparation. The mean 2 values reported vestigation to experimental design, we find above from our studies were taken from the \\x_x\q difference in basic variability of speed hanging drop preparation. Using the Fer- measurements whether observations are made guson chamber where the Paramecium's path ^t controlled temperatures in lettuce media, is not restricted to the diameter of a drop, malt media, tap water, or a salt solution at the mean z is greater, about l660/x. Using pH 6.8. Observations on single paramecia the data obtained from this chamber we gave smaller standard deviations, but the dif- plotted the mean lengths of rotations 2 ference compared to observations made on against speed and found an indication that groups of paramecia was small. Equilibra- speed and length of rotation increase to- tion after the organisms were placed in the gether. However, the scatter was great. hanging drop, gave smaller standard devi- The use of 2 to indicate changes in the ations and also a more stable mean speed. 138 Tulane Studies in Zoology Vol. 8 The mean speeds obtained here agree closely with those obtained by other investigators and lend support to the use of the change in mean speed as an index of response in cer- tain experimental situations. However, com- plete characterization of the spiral path is desirable to give information about the force and direction of the cilia activity. Summary ( 1 } Three measurements are necessary to characterize movement of a paramecium; length of the spiral, width of the spiral, and speed of the organism progressing along this path. (2) Of the three methods of estimating the actual distance traveled by a paramecium per unit of time, calculating the three di- mensional path length ( L.s ) is the most ac- curate. The distance measured along the two dimensional projection of the path may be expected to give an error of about 1 ^r com- pared with L.s; the straight line distance underestimates L.s by about 3'^- (3) Hanging drop preparations of para- mecia are characterized by rapidly changing mean speeds during early periods after for- mation (time< 180 minutes). After equi- libration more stable mean speeds are ob- tained. ( 4 ) The mean speed of P. caudatum at 25° is between 400 and 500 /x/'sec. For P. multlrwcrnmicleatum this mean is between 600 and 700 /x/sec. ( 5 ) Measurements of mean length and width of the spiral of P. rnultiniicronucle- atum in hanging drops give: length z = 1121 /J,, width a ^ 46 IX. (6) There is little advantage in meas- uring speed on many single paramecia indi- vidually as compared to groups. Appendix Error Involved in Measurement of Distance The actual distance traveled by a Para- mecium may be calculated if one assumes that the organism swims along a perfect helix. There are two other measures of dis- tance traveled which are considered less ac- curate estimates. One is the length of the curved two dimensional projection of the path, the other is the straight line distance from start to finish {z on fig. 2 ). The three dimensional distance traveled may be derived from the parametric equa- tions for a helix: z = a^ X =: a cos 6 y ^ asin ^ If L.-? is the arc length the paramecium travels during one complete rotation (B doing from 0 to 27r) then L;5= V (27ra)- + z- where a is the radius of the helix and z is the distance traveled in the direction of the major axis during one rotation. If one measures the two dimensional pro- jection of the path as shown in figure 2, the accuracy of this estimate is between z and L3. Comparison of the length of the two dimensional path, Lo with L3 may be made by also determining this length from a and z as was done for L^. If iir then the two dimensional arc length cor- responding to one complete rotation, L^ is given by /-;T(b- + a-cos-^)i/-d^ L2 ^^ 1 ;° = 4(a^ + b^^)V^j^ where 2 Ko a2 + b- Here the elliptical integral will not simplify therefore, it must be evaluated for each value of z and a from tables. ( Mathematical Tables from the Handbook of Chemistry and Physics, Ed. 9, page 238.) The relative errors, L^ - z and L.j - L2 can ~U U both be expressed as functions of the ratio a/z: Lq - Z =r L.-5 - U = where E is l-((27ra/z)- + l)-V2 1 - (2 '7r)E JT' /2 ( I -K-sin-^)'''-d^ These relative errors are shown graphically in figure 8. No. 5 Sears and Elveback: Movement of paramecia 139 12- 02- 0— 10- — =L3-Z _l L3 --- = L3-L2 c o .08- 1-3 o o. .06- o s o UJ 04- Figure 8. Magnitude of error is measure of distance related to the ratio of a to z. In data studied here the ratio a/z exceeded 0.06 for less than ten percent of the paths studied, and exceeded 0.07 in only four per- cent of these paths. This means the relative error in using distance along L2 rather than along Lg is small. References Cited Alverdes, Friedrich 1922. Studien an In- fusorien iiber Flimmerbewegung, Lokom- otion und Reizbeantwortung. Arb. Geb. Exp. Biol., 3: 1-127. BuLLiNGTON, W. W. 1925. A study of spiral movement in the ciliate Infusoria. Arch. Protistenk., 50: 219-265. Chalkey, H. W. 1930. Resistance of Para- mecium to heat as affected by changes in hydrogen-ion concentration and in inor- ganic salt balance in surrounding medi- um. U. S. P. H. S., Pub. Health Repts., 45: 481-489. Ebbecke, U. 1935. Das Verhalten von Para- maecien unter der Einwirkung hohen Druckes. Arch. Ges. Physiol., 236: 658- 661. Ferguson, Marion L. 1957. Photographic technique for quantitative physiological studies of paramecia and other motile cells. Physiol. Zool., 30: 208-215. Jennings, H. S. 1923. Behavior of the Low- er Organism. Columbia Univ. Press, New York. LUDW^IG, WiLHELM 1929. Untersuchungen iiber die Schraubenbahnen niederer Or- ganismen. Zeit. Vergl. Physiol., 9: 734- 801. Sears, D. F. 1957. Some physiological ef- fects of chemically inert gases. (Unpub- lished thesis, Univ. Rochester, Rochester, N. Y.) and W. O. Fenn 1957. Narcosis and emulsion reversal by inert gases. .Jour. Gen. Physiol., 40: 515-520. Walton, A. C. 1916. Reactions of Para- moecium caudatum to light. Jour. Animal Behavior, 6: 335-340. Abstract The investigation reports experimen- tal methods for determination of speed and rotation of paramecia. Three measures are necessary to character- ize movements of paramecia : speed of the organism, and the length and width of the path along which movement is occurring. Mean speeds of P. caudatum at 25 °C are between 400 and 500 mi- crons per second (time>180 minutes). For P. m ulti micron uclea turn these means are between 600 and 700 /^/sec. For P. multimicronucleatum the mean length of a complete rotation about the longitudinal axis is 1121 microns, the radius of the spiral 46 micions. Several factors involved in the design of experiments on movement of para- mecia were discussed. NINE DIGENETIC TREMATODES OF MARINE FISHES FROM THE ATLANTIC COAST OF PANAMA ' FRANKLIN SOGANDARES-BERNAL and LUCY McALISTER SOGANDARES, Department of Zoology, Tulane University, New Orleans, Louisiana Studies of the geographical distribution of marine Digenea in recent years have given rise to speculation regarding similarities of the trematode faunas from both American continental oceans. The first important stud- ies attempting to explain the geographical distribution of American marine Digenea were by Manter ( 1934, 1940a, 1947, 1954, 1955). Several workers, mainly Hanson (1950), Siddiqi and Cable ( I960), Sogan- dares (1959), Sparks (1957, 1958, I960), and others, have also studied the geographi- cal distribution of American marine trem- atodes. The area of the formerly submerged Isthmus of Panama, the most recent con- tinuity between the American Atlantic and Pacific Oceans, has figured prominently in explanations regarding the similarities of the trematode faunas. Previous collections of marine Digenea from Panama were made on the Pacific coast only. Almost the entire body of literature on Atlantic Digenea, on which comparisons with the Pacific Digenea are based, repre- sents studies in coastal waters of Maine, Massachusetts, North Carolina, Florida, and Louisiana; and in the islands of Bermuda; Tortguas, Florida; Bimini and Nassau, Ba- hamas; and Puerto Rico. In view of the rela- tively recent connection of the two oceans at the Isthmus of Panama we made at least a preliminary sampling of the Digenea of the Atlantic coast in this area. The following digenetic trematodes were collected from the Atlantic coast of Panama during August, I960. Unless otherwise spe- cified all measurements are in millimeters. Family BUCEPHALIDAE Bucephaloides arcuatus (Linton, 1900) Hopkins, 1954 ( figs. 1 to 7 ) Host. — Sphyraena barracuda (Walbaum); great barracuda; family Sphyraenidae. Incidence of injection. — In 1 of 1 host. Location. — Pyloric ceca. Locality. — Colon Reef, Republic of Pana- ma {new locality record}. Discussion. — Linton (1900) named and described Gasterostomum arcuatum from Sarda sarda (Bloch) in Woods Hole, Massa- chusetts. He also ( 1905 ) reported the spe- cies from Scomheromoriis regalis ( Bloch ) in Beaufort, North Carolina. In another re- port Linton (1910) briefly described (pp. 80-81; figs. 223-225) three species under the name Gasterostomum sp. from the great barracuda in Tortugas, Florida. Manter ( 1 940b ) reported Bucephalopsis arcuatus (Linton, 1900) Eckmann, 1932 from Sphy- raena barracuda in Tortguas, Florida, point- ing out that Linton's (1910) Gasterosto- mum sp. from the barracuda was confused with at least two species, Bucephalopsis longoviferus Manter, 1940 and Bucephalop- sis arcuatus. Linton (1910) had confused three species under the name Gasterostomum sp. His figures 223 and 224 respectively probably represent Bucephaloides arcuatus (Linton, 1900) Hopkins, 1954 and Bu- cephaloides longoviferus (Manter, 1940b) Hopkins, 1954, while his figure 225 is prob- ably a species of Bucephalus Baer, 1826. In 1932 Eckmann transferred Gasterostomum arcuatU7?i Linton, 1900 to the genus Buceph- alopsis Diesing, 1855. Apparently unaware of Eckmann's ( 1932 ) comb'nation, Linton (1940) subsequently reported Gasterosto- mum arcuattim from Sarda sarda. Scomber scombrus Linn., Trichiurus lepturus Linn., and Gadus morrhua Linn., in Woods Hole, Massachusetts. Hopkins (1954) reserved the genus Bucephalopsis for a larval bucephalid trematode, Ccrcaria haimeana La Caze- Duthiers, naming the genus Bucephaloides for all other species formerly in Bucepha- lopsis. Sogandares (1959) reported B//t 6'/? A - aloides arcuatus from Sphyraena barracuda in Bimini, Bahamas. Siddiqi and Cable ( I960) reported Bucephalopsis arcuatus from the same host in Puerto Rico. Yama- 1 This study was supported in part by a grant-in-aid from the Society of the Sigma Xi. 142 Tulane Studies in Zoology Vol. 8 Fig:ures 1-7. B^cephaloides areitatv.s:. 1, 2. Dorsal and ventral views of whole mounts. 3. Ventral view of anterior portion of forehody. 4, 5. Central and dorsal views of {geni- tal atrium showing genital lobe and portion of cirrus sac. 6. Dextrolateral view of geni- tal atrium showing genital lobe and portion of cirrus sac. 7. Uterine eggs. Unless other- wise specified, all figures were drawn with the aid of a Leitz camera lucida for inclined microscopes. The projected scale has the approximate value in millimeters. guti (1958) regarded Bucephaloides a syn- onym of Bucephalnpsis. Since we do not know into what genus Cer carta haimeana will develop, Hopkins' (1954) views will be followed until evidence proves otherwise. The Panama specimens of B. arcuatus have eggs resembling those of B. longovi- ferus, most eggs ( fig. 7 ) measuring from No. 5 Sogandares and Sogandares: Digenetic trematodes 143 26 to 29 by 9 microns. One egg (fig. 7) Manter (1940c) reported H. mutahile from measured about 24 by 17 microns. The Ltitjanus viridis (Val. ) and ? Mycteroperca Panama specimens differ from B. longovi- xenarcha Jordan in the Galapagos Islands. ferus in details of the genital lobes (figs. 4- Sogandares ( 1959) reported H. mutahile 6) and a uterus that never extends posteri- from Epinephelus striatus (Bloch), Haenu/- orly beyond the genital atrium (figs. 1, 2) Ion sciurus (Shaw), Lutjanus synagris. and or to the anterior sucker (figs. 1-3). The Petronietopon cruentatus (Lacepede) in Bim- Panama specimens differ from Manter 's ini, Bahamas. Siddiqi and Cable (I960) re- (1940b) redescription of B. dnv/^^/^j- mainly ported H. nintabile from Ltitjanus analis, in egg size, in the more anterior extent of L. jocu. L.. griseus, L. apodus, and Ocyurus the uterus, and by possessing more vitelline cbrysurus in Puerto Rico. They also de- follicles. Egg size is a variable character in scribed two new species, Hamacreadimn certain bucephalids and cannot usually be lintoni from Epinephelus striatus and Ceph- relied upon to show species differences. The alopholis fulvus, and H. longisaccum from anterior extent of the uterus is sometimes Epinephelus adscensionis in Puerto Rico. a more reliable systematic character. The The descriptions of H. lintoni and H. longi- anterior uterine extent of our specimens saccu7n both fall within the range of vari- ( figs. 1-3) intergrades with Manter's (1940b) ation observed for H. mutahile. Further- redescription of B. arcuatus and extends the more, H. mutahile is known from Epineph- range. The number of vitelline follicles is elus striatus in Bimini, Bahamas. Nagaty difficult to count in our material because we ( 1941 ) reported H. ynutabile from Serranus cannot be sure if what frequently appears merra (Bloch) (^Epinephelus merra) , to be a separate follicle overlapping an- Lethrinus mahsena Forsk., L. nehulosus Cuv. other follicle, is in reality a single branched and Val., Teuthis marmorata Giinther, and follicle, or one which is cytolized. Further Lutjanus flui'iflamma (Forsk.) (=: Diacope study of live B. arcuatus from the Panama fluviflamma) in the Red Sea. He also be- Atlantic and more northern waters may lieved Hamacreadium epinepheli Yamaguti, show that there are actually three species of 1934, from Epinephelus akaara Temm. and Bucephaloides in Sphyraena barracuda. The Schl. and Lethrinus haematopterus Temm. present evidence seems to indicate that we and Schl. in Japan, to be a synonym of H. are probably dealing with a different popu- mutahile. lation of B. arcuatus. H. mutahile has been reported from at Eamtly OPECOELIDAE ^^^'' "^"f ^^" ^'^^^^^"^ ^^'' f^j' "f '^^''^' c t X I ni • >, • about 42 percent are m the ramily Lut- Subfamtly Flagtopormae ■ i -,/- • , o iic-r ■' . janidae, 26 percent m the Serramdae, 15.7 Uamacreadmm mutahile Lmton, 1910 ^^^^^^^ -^^ ^he Lethrinidae, 10.52 percent in (rigs. 5 to 15) j-j^^ Pomadasyidae, and 5.25 percent in the Host. — Ocyurus chrysurus (Bloch); yel- Acanthuridae. The major host groups are low-tail; family Lutjanidae. the lutjanids, serranids and lethrinid fishes. Incidence of infection. — In 2 of 2 hosts. The pomadasyids and acanthurids are pos- Location. — Intestine. sibly accidental hosts of H. mutahile. though Locality. — Galeta Point, Republic of Pana- the pomadasyids are related to the lutjanids, ma [new locality record}. serranids and lethrinids. Discussion. — Hamacreadium mutahile was Our specimens of H. ynutahile have only reported from Lutjanus griseus (Linn.), L. slightly lobed or smooth testes and the apodus (Walbaum), and Anisotrernus vir- ovaries are either smooth or deeply lobed ginicus (Linn.) at Tortugas, Florida by Lin- (figs. 8-15). The cirrus sac does not over- ton (1910). While at Tortugas, McCoy lap the acetabulum in one preadult (fig. (1929, 1930) experimentally obtained adults 12) and usually comes into contact with or of H. mutahile from Lutjanus griseus and overlaps the acetabulimi by about half its Ocyurus chrysurus, Manter (1947) also re- length in adults (figs. 8-10), and preadults ported the following additional hosts for H. (figs. 11, 13-14), extending to beyond the mutahile at Tortugas: Lutjanus jocu (Bloch posterior border of the acetabulum in one and Schneider), L. analis (Cuv. and Val.), adult contracted specimen (fig. 15). The and L. synagris (Linn.). In another paper genital pore position of our 12 H. mutahile 144 Tulane Studies in Zoology Vol. 8 Figures 8-14, Hamacreadium mutahile. 8, 9. Ventral views of whole mounts. 10. Dorsal view of much contracted specimen. 11-14. Ventral views of preadults showing: variation in posterior extent of cirrus sac. specimens is sinistral. The esophagus varies considerably in length, depending mainly upon the degree of contraction of the fore- body (figs. 8-15). The vitellaria of our specimens are almost always confluent in the region of the cecal bifurcation. The ex- cretory vesicle usually extends to the cecal bifurcation. Yamaguti (1958) lumped several families of trematodes under the name Allocreadiidae. We are not following Yamaguti because the opecoelid trematodes, while showing simi- larities with adult allocreadiids, are a well defined group with cotylomicrocercous cer- cariac. Also, we are not entirely in agree- ment with the more recent views of Dollfus No. 5 Sogandares and Sogandares: Digenetic trematodes 145 (I960) who split the Opecoelidae into sev- eral families. The more conservative views of Manter (1947) and of Cable (1956) are followed here. Fa7nily HAPLOSPLANCHNIDAE Haplosplanchnus iScbikhobalotrema) acutus (Linton, 1910) Manter, 1937 (fig. 16) Host. — Abiidefduf saxatilis (Linn.); ser- geant-major; new host record; family Poma- centridae. Incidence of injection. — In 1 of 1 host. Location. — Intestine. Locality. — Galeta Point, Republic of Pana- ma [new locality record}. Discussion. — Sogandares (1959) pointed out that H. acutus is a parasite of needle- fishes ( family Belonidae ) and reviewed the occurrence of this species in different hosts and localities. The record of H. acutus by Manter (1940c) from Kyphosus elegans ( Peters ) in the Galapagos Islands, by So- gandares (1959) homThyrinops pachylepis (GiJnther) in Panama Bay, and from Abu- defduf saxatilis in the Panama Atlantic prob- ably represent accidental infections since only one specimen was found in each case. Our specimen from A. saxatilis had no eggs in the uterus, though it agreed in all details with material of the same species from Bimini, Bahamas and Panama Bay. The Russian workers Skrjabin and Gus- chanskaja (1955) named the genus Schik- hobalotrerna for Haplosplanchnus acutus (Linton, 1910) Manter, 1937, and syn- onymized Laruea Srivastava, 1939 with Hap- losplanchnus Looss, 1902. Manter (1957) independently arrived at the same conclu- sions utilizing somewhat different criteria from those of Skrjabin and Guschanskaja (1955). Yamaguti (1958) recognized Schikhobalotrema. but regarded Laruea a valid genus. Siddiqi and Cable I960 recog- nized Schikhobalotrema with some reserva- tions even though they named two new spe- cies and reported three others in this genus. These authors stated that, while they ac- cepted Skrjabin's and Guschanskaja's ar- rangement, it would not be surprising to find intermediate species which would invalidate Schikhobalotrema. Skrjabin and Guschan- skaja (1955) believed that Schikhobalotre- yna could be separated from Haplosplanch- nus on the basis of the anterior reduction of the vitellaria, presence of a ventral ace- tabular peduncle, and a poorly developed seminal vesicle in the latter genus. Manter's (1957) views were that Haplosplanchnus pachysomus (Eysenhardt, 1829) Looss, 1902 (type species), H.. pmii Srivastava, 1939, and H. caudatum (Srivastava, 1939) Skrja- bin and Guschanskaja, 1955 (^^ Laruea cau- data ) , all occur in mullets ( genus Aiugil Linn. ) , possess uterine eggs with occulate miracidia, and have greatly reduced vitel- laria. He also suggested that the other spe- cies of Haplosplanchnus, forms occurring in acanthurid, spariosomid (=: family Scaridae), scarid and girellid fishes, with extensive fol- licular vitellaria, "(which tend to become tubular as happens in the Haploporidae ) ", and have uterine eggs with undeveloped embryos, should probably be placed in a separate genus. He did not name a new genus for these forms. Manter ( 1957) was unaware of Skrjabin and Guschanskaja ( 1955 ) because at that time political bound- aries precluded free exchange of scientific information between Russian and American scientists. The fact remains that the differ- ent authors arrived at the same conclusions independently and through the use of dif- ferent criteria. We have examined many live and preserved specimens of H. acutus, ( type species of Schikhobalotrema ) , from needlefishes in Bimini, Bahamas. The vitel- laria of H. acutus are frequently diffuse and poorly developed anteriorly. While there is a tendency for the vitellaria to become tubu- lar in some species of Haplosplanchnus. as Manter ( 1957 ) suggests, the species of this genus show various degrees of intergrada- tion of this character. We do not believe that the developmental rate of uterine eggs with occulate miracidia should have generic value, at least until we know if fully de- veloped and passed eggs of H. acutus also possess occulate miracidia. The fact that the species with occulate miracidia in the uter- ine eggs coincidentally occur in Mugil spp. may indeed be suggestive that these species are closely related, yet not necessarily gen- erically distinct from other species in which the miracidia in the uterine eggs have not developed completely. The only life history study in the Haplosplanchnidae is that of H. acutus by Cable ( 1954) and he was un- able to observe (or at least did not report) fully embryonated eggs of this species. The 146 Tulane Studies in Zoology Vol. 8 Figures l')-21. 15. Ilatnacreadium mutabile, dorsal view of much contracted specimen. 16. Hdiilos/iliDirliiiKs {Scliikli(ih(tlof)eiii(i) (iciitiis, dextrolateral view of whole mount. 17. llu/ilusplaiichnKS (Scliikhobulotermu) jjuinucciitri, ventral view of whole mount. 18. Multitestis chaetodoni from Chaetodon ocellatnn, ventral view. 19. MnltiteHtis chae- tuiiitti from Chaetodon capisfratnn, ventral view. 20. Midtitestis chuetodoni from Chae- tudoii ca/jistratHS, sketch of cirrus sac showing preprostatic musculai' bulb when confused with anterior prostatic vesicle. 21. Neouijocreadiiim coili, ventral view of a mechanically excysted metacercaria. No. 5 Sogandares and Sogandares: Digenetic trematodes 147 length of the acetabular peduncle and poorly developed seminal vesicle are characters which vary in degree only, thus could hardly be considered generic. Another view is that the overlap of certain characters between the species of Schikhobalotrema and Haplos- planchnus gives further evidence of the closeness of relationship between the two genera. The question remains at present a matter of opinion. Precluding a knowledge of life histories, when closely allied species groups of adult trematodes show morphological intergrada- tion allowing partial but not complete segre- gation of these groups (clear-cut characters found in only one species group), we pre- fer to regard these species groups as sub- genera. A moderate approach in naming genera eliminates the need of hastily erect- ing higher categories (often with insuffi- cient evidence) such as subfamilies which may later tend to confuse the issue. Sub- genera have permanent status in nomen- clature and show relationships of the species groups without the necessity of creating higher categories. We presently recognize the following dis- position of the species of Haplosplanchnus: ( 1 ) subgenus Haplosplanchnus, H. (H.) pacbysomus (Eysenhardt, 1829) Looss, 1902, H. (H.) purii Srivastava, 1939; (2) subgenus Laruea, H. (L.) caudatum Srivastava, 1939; and (3) subgenus Schikhobalotrema, H. (S.) acutus (Linton, 1910) Manter, 1937, H. iS.) adacutum Manter, 1937, H. (S..) brachyurus Manter, 1937, H. (S.) girellae Manter and Van Cleave, 1951, H. (5.) kyp- hosi Manter, 1947, H. (5".,) obtusum (Lin- ton, 1910) Manter, 1937, H. {S.) poma- centri Manter, 1937, and H. {S.) sparioso- mae Manter, 1937. As Manter (1957) suggested, the hap- loporids may be related with the haplos- planchnids. Adult specimens of both fam- ilies sometimes possess sensory papillae on the oral suckers, and except for the presence of a single cecum in Haplosplanchnus and a hermaphroditic sac in Haploporus Looss, 1902, are similar. We do not know the significance of the similarities between these families. The similarities may represent con- vergence which is frequently encountered in the Digenea. Haplosplanchnus I Schikhobalotrema) pomacentri Mumer, 1937 (fig- 17) Hosi.—Pnviacentrus let/cnstictus Miiller and Troschel, beau gregoire; and Pomacent- rus planifrons ( Cuv. and Val. ) ; petite jac- quette, new host record; family Pomacentri- dae. Incidence of injection. — In 1 of 4 P. leu- costictus and 2 of 2 P. planifrons. Location. — Intestine. Locality. — Galeta Point, Republic of Pan- ama [new locality record]. Discussion. — H. pomacentri formerly was known only from fishes of the genus Poma- centrus; from Tortugas, Florida, in P. leu- costictus and P. xanthurus Poey, ( Manter, 1937, Manter, 1947), and from Galapagos Islands, in P. rectifraemim Gill, (Manter, 1940c). One specimen of H. pomacentri in our collection lacks a testis. Family LEPOCREADIIDAE Subfa?nily Lepocreadiinae Multitestis chaetodoni Manter, 1947 (figs. 18-20) Hosts. — Chaetodon capistratus Linn.; four- eyed butterfly fish; and Chaetodon ocellatus Bloch; common butterfly fish; family Chae- todontidae. Incidence of infection. — In 4 of 5 C cap- istratus and 2 of 2 C. ocellatus. Location. — Intestine. Locality. — Galeta Point, Republic of Pan- ama [new locality record]. Discussion. — The only other record of Multitestis chaetodoni Manter, 1947, is the original description of specimens from Chae- todon capistratus and C. ocellatus in Tortu- gas, Florida. According to Manter ( 1947 ) , Linton's (1910; p. 115) Distoynum sp. is M. chaetodoni. Manter ( 1947 ) described a bipartite prostatic vesicle for M. chaetodoni. Some of our specimens which are darkly stained ap- pear to have a bipartite prostatic vesicle. We obtained a series of 24 specimens of M. chaetodoni from C. ocellatus and 6 from C. capistratus. and have observed that what appears to be the anterior prostatic vesicle in darkly stained specimens is a sphincter muscle at the junction of the prostatic vesi- cle with the base of the cirrus (fig. 20). If the anterior border of this sphincter muscle 148 Tulane Studies in Zoology Vol. 8 Figures 22-ol. 22. H in-lc!/t)('»i(itoi(ic!i chaetodoni from Chnctodo)i s!)-i(itits, ventral view. 23. //. cliuetoduiii from C. ,s1 ridtit.^, sketch of dorsiil view of terminal genitalia, dashed lines represent outline of acetabulum. 24. H.chaetodoni from C. striatus, eggs with polar filaments partially omitted. 25. //. chiwtodotii from C. ocellutiia, eggs with polar fila- ments partially omitted. 26. Sii)liodera ritialedivardsi, ventral view of whole mount. 27. Tht'letiKiit tHdyttasuccion, sp. nov., ventro-lateral view of holotype, dashed lines repre- sent the position occupied by the uterus. 28. T. inagiKtsacciini, lateral view of vitelline follicles, dashed lines represent optical sections of anterior and posterior follicles. 29. T. mafjvasaccHtH, optical reconstruction of vitelline follicles as they would presumably appear in ventral view. 30. T. of terminal genitalia. nidyttasacciitu, uterine eggs. 31. T. itKUjiidsarcitin, lateial view No. 5 Sogandares and Sogandares: Digenetic trematodes 149 is contracted, allowing sperm to collect and swell its internal sperm duct, the muscular bulb could easily be confused with a pros- tatic vesicle. The cytological details of the wall of the sphincter bulb further suggest that this structure is not a prostatic vesicle. Our specimens had from 9 to 11 testes. Subfamily Homalometrinae Neoapocre odium coili (Sogandares, 1959) Siddiqi and Cable, I960 (fig. 21) Host. — Halichoeres bivitattus (Bloch); slippery dick; family Labridae. Incidence of infection. — In 1 of 2 hosts. Location. — Intestine. Locality. — Galeta Point, Republic of Pan- ama [new locality record]. Discussion. — The metacercariae of N. coili reported here were encysted in muscle fragments of a crustacean (probably a small snapping shrimp) found in the intestine of H. bivittatus. The cysts were teased apart with a needle and the metacercariae fixed with A.F.A. between a coverslip and slide. Since we did not have a compound micro- scope with us, the flame cell pattern and other important details of the live specimens were unobserved. Sogandares (1959) noted that certain spe- cies of Apocreadium {A. bravoi Sogandares, 1959, A. coili Sogandares, 1959, and A. an- gustum Sogandares, 1959) possessed oral suckers with 2 lateral fleshy lobes, and vitel- laria confluent anterior to the acetabulum. Siddiqi and Cable (I960) named the genus Neoapocreadium for these species. The dis- tinctive oral sucker immediately related our specimens to the genus Neoapocreadium. Comparison of our Panama specimens with preadults of A. coili and other Neoapocre- adium spp. collected by one of us ( F.S. ) in Bimini, Bahamas, leaves little doubt of the specific identity of specimens in the present collection. The type material of A. coili is from Balistes capriscus Gmelin and B. vetula Linn., in Bimini, Bahamas. Siddiqi and Cable (I960) reported N. coili from B. vetula in Puerto Rico. Faynily MONORCHllDAE Hurleytrematoides chaetodoni ( Manter, 1942) Yamaguti, 195S (figs. 22-25) Hosts. — Chaetodon capistratus Linn.; four- eyed butterfly fish; Chaetodon ocellatus Bloch; common butterfly fish; and Chaeto- don striatus Linn., banded butterfly fish; new host record; family Chaetodontidae. Incidence of infection. — In 2 of 5 C. cap- istratus; 1 of 2 C. ocellatus; and 1 of 1 C. striatus. Location. — Intestine. Locality. — Galeta Point, Republic of Pan- ama [new locality record]. Discussion. — Manter (1942, 1947) de- scribed and reported Hurleytrema chaeto- doni from Chaetodon ocellatus and C. cap- istratus in Tortugas, Florida. The metraterm of his type specimens was about 3/4 length of the cirrus sac. The metraterm in our material shows considerable extension or contraction (figs. 22, 23), sometimes agree- ing in proportion with the type description. The egg sizes of H. chaetodoni from Chae- todon striatus and C. ocellatus (figs. 24, 25) overlap, though they are considerably shorter (about 30 to 32 vs., 40 to 46 microns) than those reported by Manter (1942). The uni- polar filament-egg ratio of our specimens agrees with Manter 's ( 1942 ) description. Although we have no material of H. chae- todoni from localities intermediate between Tortugas and Panama, these variations in egg size may represent population differ- ences. Siddiqi and Cable (I960) reported H. chaetodoni from Chaetodon capistratus in Puerto Rico. Yamaguti (1953) erected a new genus Hurleytrematoides for H. chaetodoni. The description of the type species of Hurley- trema, H. ovocaudatum Srivastava, 1938, seems to differ from that of H. chaetodoni mainly in the type of cirrus and metraterm spines, in egg size, and in a more posterior distribution of the vitelline follicles. Pro- fessor H. W. Manter ( personal communica- tion) adds another distinguishing character and recognizes Hurleytrematoides on the basis of a bipartite seminal vesicle. We are following his views here in recognizing Hurleytrematoides. Family CRYPTOGONIMIDAE Subfamily Siphoderinae Siphodera vinaledwardsi (Linton, 1901) Linton, 1910 (fig. 26) Host. — Lutjanus synagris ( Linn. ) ; lane snapper; and Ocyurus chrysurus ( Bloch ) ; yellow-tail; family Lutjanidae. 150 Tulane Studies in Zoology Vol. 8 Incidence of infection. — In 2 of 2 L. syna- gris and 2 of 2 O. chrysurus. Location. — Intestine. Locality. — L. synagris from Cristobal Yacht Club basin and Galeta Point and O. chrysjirus from Galeta Point, Republic of Panama [new locality record}. Discussion.— T\\Q distribution of S. vinal- edwardsi was recently reviewed by Sogan- dares and Hutton (1959). These authors neglected to cite the following records: Bravo (1956) in Lutjanus guttatus (Stein- dachner) from Baja California, Mexico; Sparks (1957) in Ocyurus chrysurus from Nassau, Bahamas; and Sogandares (1959) in Lutjanus synagris from Bimini, Bahamas. Siddiqi and Cable (I960) reported S. vinal- ed ward si from Lutjanus synagris and L. analis from Puerto Rico. S. vinaledivardsi is a widespread species in the American Atlantic and utilizes various carnivorous definitive hosts, mainly lutjanid, batrachoidid, and pomadasyid fishes. Our specimens from the Atlantic coast of Panama compare favorably with those col- lected in other localities in Florida and Bimini, Bahamas. Family HEMIURIDAE Subfamily Lecithasterinae Theletrum magnasaccum, sp. nov. (figs. 27-31) Host. — Ahudefduf saxatilis (Linn.); ser- geant-major; family pomacentridae. Incidence of infection. — In 1 of 1 host. Location. — Stomach. Locality.. — Galeta Point, Republic of Pan- ama. Holotype. — U. S. Nat. Mus. Helm. Coll. No. 39500. Diagnosis (based on one specimen). — Theletrum: Body elongate, approximately 3.15 long by 0.59 wide at midbody. Cuticle smooth, bearing no papillae. Forebody 0 66 lonR. Oral sucker subtcrminal, 0.16 long by 0.17 wide. Preorai lip present. Acetabulum 0.44 long by 0.42 wide. Sucker ratio about 1:2.4. Prepharynx so short that it appears absent. Pharynx roundish, 0.07 long by 0.10 wide. Esophagus very short, almost appear- ing absent. Ceca extending, one on each side of body, to posterior end of body. Genital pore ventral, median, at level of mid- pharynx. Sinus sac connecting directly with genital pore, muscular, pear-shaped; O.IO long by 0.10 at widest portion. Testes equa- torial, oblique; sinistral testis anteriormost, 1 /7 distance from acetabulum to posterior end of body, oval in shape, about 0.14 long by 0.19 wide; dextral testis posteriormost, about 1 3 distance from acetabulum to pos- terior end of body, roundish in shape, about 0.15 long by 0.17 wide. Seminal vesicle in- tercecal, about 1/3 distance from acetabulum to anterior end of body, bipartite; connect- ing with a short prostatic vesicle which is surrounded by prostate cells and is about 1/2 length of the sinus sac with which it connects (fig. 31). Ovary slightly less than 1 2 distance from acetabulum to posterior end of body, oblong in shape, about 0.12 long by 0.13 wide. Seminal receptacle con- spicuous between posterior testis and dorsal aspect of ovary, spherical and larger than ovary. Vitellaria of two compact lobes (figs. 28, 29), anterior vitellarium bilobed, pos- terior vitellarium unlobed; immediately pos- terior to and in contact with ovary. Uterus with large sac-like coils which are difficult to trace, mainly intercecal, descending from ovarian complex to fill most of postovarian area, ascending to cover partially the vitel- laria, seminal receptacle, ovary, and testes, intruding between ovary and posterior testis and foretestis, the sac-like coils disappearing anterior to acetabulum where uterus per- forates the sinus sac adjacent to the connec- tion with prostatic vesicle. Eggs thick- shelled, varible in shape and size (fig. 29), about 17.4 to 31.9 microns long by 11.6 to 14.0 microns wide. Excretory vesicle not observed. Discussion. — The genus Tbeletrum Lin- ton, 1910 resembles Aponurus Looss, 1907, differing mainly by possessing 2 or 3 in- stead of 7 or 8 prominent vitelline lobes. Studies of additional species may show that these two genera are synonymous or that Theletru7n is a subgenus at best. At present the vitelline lobation appears to be a stablp, though sometimes difficult to observe, char- acter. Yamaguti ( 1958) reexamined Lin- ton's type material of 7'. fustifor?ne and be- lieved that, "the ejaculatory duct and metra- term open into a genital atrium." Yamaguti also stated, ". . . the cirrus poucii could not be made out with certainty." Manter (1947) studied specimens of T. fustiforme from the type host and locality and did not report or picture a genital atrium. Instead he stated, No. 5 Sogandares and Sogandares: Digenetic trematodes 151 Table 1. Nine digenetic trematodes from the Atlantic coast of Panama and their distribution in the American Pacific and Atlantic 2 Localities Species Tropical Tropical American American Atlantic other Pacific than Panama — + + + + 4- + + + + + + 4- American Atlantic from Woods Hole, Mass. to Beaufort, N. C. Bncephaloides arcuatus Ham acreadiu tn m u ta bile Haplosplanchnus acutus Haplosplanchniis pomacentri Multitestis chaetodoni Neoapocreadium coili Hnrleytrema chaetodoni Siphodera vivaledwardsi Theletrum magnasacciim + + -( + ) denotes presence and ( — ) absence of the species. "The seminal vesicle is a long coiled tube, slightly overlapping the acetabulum; the pars prostatica is rather short, its distal half sur- rounded by a compact but conspicuous pros- tatic gland. The sinus sac is cylindrical, almost straight, with thick walls, containing a few gland cells." Our study of the terminal genitalia of T. magnasaccum lends allied support to Manter's (1947) observations and redescription of the terminal genitalia of T. fustiforme. The "prostate gland" de- scribed by Manter is doubtless a prostatic vesicle surrounded by prostate cells. There are three species in Theletrum, T. fustiforme Linton, 1910 (type species), T. lissosomum Manter, 1940 and T. gravidum Manter, 1940. T. magnasaccum resembles T. grav'dum and T. lissosomum but differs by possessing a conspicuous hermaphroditic sac, two vitel- line lobes, a bipartite seminal vesicle, and other small differences which are at present difficult to evaluate due to the present shortage of material. T. magnasaccum dif- fers from T. fustiforme by lacking the post- acetabular ventral folds and papillae as de- scribed by Manter (1947), in genital pore position and by possessing a bipartite semi- nal vesicle which does not overlap the acetabulum. ' ^ T. magnasaccum is closely related with T. gravidum, from the same host genus (Adu- defduf) in the Pacific, and probably repre- sents its geminate species in the Atlantic. The vitelline lobes of T. magnasaccuin initially resembled those of Aponurus when viewed laterally. Careful focussing with the microscope showed that the mass is com- posed of two follicles (fig. 28), the anterior- Table 2, Host species examined and trematodes found. Ahudefdiif xarntilis (Linn.) Haploxplnnrhnus acvliia (Linton, 1910) Manter. 11)37 Theletrum mntpinsnccum ( this paper) Aeantlnirus ehinin/iix ( Bloch) no trematodes found Clioetodon enpistratu,s Linn. Hiirlei/trematoifles chaetodoni (Manter. 1942) Yamasuti, 19.5.S Multitestis chaetodoni Manter, 1947 Chaetodon oeellatus Blocli Hurleytrematoides chaetodoni (Manter. 1942) Yamagiiti. 19.53 Multitestis chaetodoni Manter, 1947 Chaetodon striatus Linn. Hurleytrematoides chaetodoni (Manter, 1942) Yamaguti, 1953 Eueinostomus californiensis (Gill) no trematodes found Gi/mnothorax funehris Ranzani no trematodes found Halichoeres birittatus (Bloch) Seoapocreadium coili (Sogandares, 19.j9) Siddiqi and Cable. 1960 Lutjaniis f/riseus ( Linn. ) one trematode found but lost by maceration, probably a Metadena sp. Lutjanus synagris (Linn.) Siphodera rinaledirardsi (Linton. 1901) Linton, 1910 Ocyurus chrysurus (Bloch) Hamaereadium mutahile Linton. 1910 Pnmarentrus leucostictus Muller and Troschel Haplosplanchnus pomacentri Manter. 1937 Pomacentrus planifroiis (t'uvier and Valenciennes) Haplosplanchniis pomacentri Manter, 1937 Sphyraena barracuda (Walbaum) Buccphaloides arcuatus (Linton. 1900) Hopkins. 19.54 Thalassoma bifasciatum (Bloch) no trematodes found most is apparently bilobed. Figure 29 shows an optical reconstruction as the vitelline lobes would presumably appear in frontal view. One striking feature about T. magnasac- cum is the size and shape of the eggs. Fig- ure 30 shows three different types of eggs, from the same portion of the uterus, which we observed. Care was taken to assure that 152 Tulane Sfudies in Zoology Vol. 8 these eggs were not tilted, creating an il- life cycle in the family Haplosplanchni- lusion of shortness. The majority of the ^ae. Jour. Parasit., hO: 71-76. uterine eggs were of the narrow, elongate, — - -— ;- 1956. Opisthoiehes dw- , J dontis n. sp., its development m the imal sausage-shaped type. ^^^^^ ^h^ affinities of some amphisto- The name 7nagnasaccum is for the large matous trematodes from marine fishes sinus sac ( w^/^«rf = large ) { sacami = s^c) . and the allocreadioid problem. Parasit- Manter's and Pritchard's (I960) views ohgy, 46: 1-13. regarding the higher categories of the Dollfus R. Ph I960. Recherches experi- .r ■ Pj 1 L r II J • 1 • mentales suv Nicoll a qallico (R. Ph. Doll- Hemiundae have been followed in placing f^,g ^^^^^ ^ Ph Dollfus 1958, sa cercaire Theletrum in the Lecithasterinae. cotylicerque et sa metacercaire prc^iin- etique. Observations sur la famille des ~ ^ T^ Coitocaecidae Y. Ozaki 1928, s. f. Coi- The Geographic Distribution of tocaecinae F. Poche 1926, Trematodi DiGENEA Reported in Podocotyloidea et sur les cercaires coty- THIS Paper licerques d'eau douce et marines. Ann. ~ ,. ^ , , A ■ I- I ■ Parasit. Hum. et Comp., 3h: 595-622; Table 1 shows the American distribution g^. 65.117, of the Digenea reported here. Six species e^kmann, F. 1932. Beitrage zur Kenntnis are known only from the Atlantic Ocean, des Trematodenfamilie Bucephalidae. while four are shared with the Pacific. Zeitschr. Parasit., 5: 94-111. Eight species are found in other tropical Hanson, M. L. 1950. Some diRenetic trem- American Atlantic localities, two of these atodes of marine^ fishes from Bermuda. r , wr J TT I Tkj Proc. Helm. Soc. Wash., 17: /4-88. species as far north as Woods Hole, Massa- ,, c tt ior< rrn a ^ ' Hopkins, S. H. 1954. The American species cnusetts. ^f trematode confused with Bucephalus The present sample is too small to deter- (Bucephalopsis) haimeanus. Parasitol- mine significant faunal differences. We be- offlfy 44: 353-370. lieve that the digenetic trematode fauna Linton, E. 1900. Fish parasites collected fr^^ rU^ Afior,^;^ ^.^oc.^ ^( Do^o.v,o „,M -^ at Woods Hole in 1898. Bull. U. S. Fish. from the Atlantic coast of Panama will re- ^^^^^^^ ^^g^g^^ ^g. 267.304, 121 figs. veal a closer resemblance to that of Tortu- 1905 Parasites of fishes gas, Florida, and the Bahamas Islands than of Beaufort, North Carolina. Bull. V. S. to that from the Pacific coast of Panama. Biir. Fish. (1904), 24: 31-428, 249 figs. The fish and molluscan fauna of Tortugas, 1910. Helminth fauna of Florida, and the Bahamas Islands is more like T)ry Tortiigas 2 Trematodes. Carnegie .u . <: .u A.I • 1 1 D r J f /"»'. Wash., Puhl. No. 133 Papers Tor- that of the Atlantic than the Pacific side of ^^^^^ Lab. 4:) 11-98, 241 figs. Panama. Even though our sample was small, ^q^q_ Trematodes from every fish host, except Po77iacentrus plant- fishes mainly from the Woods Hole region jrons occurs in Tortugas, Florida, and the Massachusetts. Proc. U. S. Nat. Mus., Bahamas Islands. Table 2 lists the host spe- ^^- H-^^, 351 figs. cies examined and trematodes found. Manter, H W. 1934. Some digenetic trem- atodes of deep-water fish 01 Tortugas, c Florida. Carnegie Inst. Wash. Puhl. No. bUMMARY 435 (Papers Tortugas Lab. 27): 257-345. Nine digenetic trematodes, including the 1937. The status of the description of a new species, Theletrum trematode genus Deradena Linton with w^gw^J^ca^;^^, (Hemiuridae: Lecithasterinae), a description of six species of f/rr/>/o.s-- * 1 r rr • r • plauchiius Looss (Trcmatoda). Skrjabin are reported from fifteen species of marine y,,,, y^L (Moscow: U.S.S.R.) : 381-387. fishes of the Atlantic coast of Panama. The 1940a. The geographical systematic status, distribution, hosts, and new distribution of digenetic trematodes of information on the morphology of each marine fishes of the tropical American trematode species is discussed. lu^. '^""" ^^""''"''' ^'"'' ^^''^'" ^'' References Cited 1940b. Gasterostomes Tj„.„ TT HT mrc m i- J 1 (Trematoda) of Tortugas, Florida. Car- Bravo-Hollis, M 1956. Trematodos de ,,cjie Inst. Wash. Publ. .\o. 'yZi {P-apers peces mannos de Aguas Mexicanas. XI Tortugas Lab., J5) : 1-19. Lstudio de 1 / digeneos de las costas del Pacifico, incluyendo seis especies nuevas 1940c. Digenetic trem- y un genero nuevo. An)i. Inst. Biol. atodes of fishes from the Galapagos (Mexico), 27(1) : 245-277. Islands and Neighboring Pacific. Allan Cable, R. M. 1954. Studios on marine di- Hancock Pac. Exp., 2: 329-497, 136 figs. genetic trematodes of Puerto Rico. The - - 1942. Monorchidae (Trem- No. 5 Sogandares and Sogandares: Digenetic trematodes 153 atoda) fishes of Tortugas, Florida. Trans. Amer. Micros. Soc, 61 : 349-360. \ 1947. Dig:enetic trem- atodes of marine fishes of Tortugas, Florida. Amcr. Midi. Nat., 38: 257-416. 1954. Some digenetic trematodes of fishes from New Zealand. Trans. Roy. Soc. N. Z., 8.5: 475-568. 1955. The zoogeography of trematodes of marine fishes. E.rp. Parasit., U: 62-86. 1957. Host specificity and other host relationships among the digenetic trematodes of marine fishes. Premier Syniposiani sur la Specif icite Parasitaire des Parasites de Vertebres (Neuchatel: Suisse): 185-196. and Pritchard, M. H. 1960. Some hemiurid trematodes from Hawaiian fishes. Proc. Helm. Soc. Wash., 27: 87-102. McCoy, O. R. 1929. The life history of a marine trematcde, Hamacreadiiim ntnta- bile Linton, 1910. Parasitology, 21: 220- 225. 1930. Experimental stud- ies on two fishes trematodes of the genus Hamacreadiiim (family Allocreadiidae) . J oar. Parasit., 17: 220-225. Nagaty, H. F. 1941. Trematodes of fishes from the Red Sea. Part 2. The genus Hamacreadium Linton, 1910 (fam. Allo- creadiidae) with a description of two new species. .Joar. Egypt. Med. Assoc, 2U: 330-310. SiDDiQi, A. H. and Cable, R. M. 1960. Di- genetic trematodes of marine fishes of Puerto Rico. N. Y. Acad. Sci., Sci. Sur- vey Porto Rico, 17: 258-368, 139 figs. Skrjabin, K. J. and Guschanskaja, L. K. 1955. Trematodes of Animals and Man. Vol. II. Movska, U.S.S.R. Sogandares -Bernal, F. 1959. Digenetic trematodes of marine fishes from the Gulf of Panama and Bimini, British West Indies. Tulane Stud. Zool., 7: 70-117. and HuTTON, R. F. 1959. Studies on helminth parasites of the Coast of Florida. I. Digenetic trematodes of marine fishes from Tampa and Boca Ciega Bays with descriptions of two new species. Btdl. Mar. Sci. Gulf Carib., 9: 53-68. Sparks, A. K. 1957. Some digenetic trem- atodes of marine fishes of the Bahama Islands. Ibid., 7: 253-265. 1958. Some digenetic trematodes of Grand Isle, Louisiana. Proc. La. Acad. Sci., 20: 71-82. 1960. Some aspects of the zoogeography of the digenetic trem- atodes of shallow-water fishes of the Gulf of Mexico. Lib. Homm. Caballero, Inst. Polytecnico Nacional (Me-vico), pp. 285-298. Yamaguti, S. 1953. Systema Helmintlium. Part I. Digenetic trematodes of fishes. Tokyo, 405 pp. 1958. Systema Helmintli- um. Vol. I. The digenetic trematodes of vertebrates. Parts I and II. Interscience Publishers, 1575 pp. Abstract Nine digenetic trematodes of marine fishes from the Atlantic coast of Pana- ma are reported: Bucephaloides ar- cuatus (Linton, 1900) {Bucephalidae) , from the pyloric ceca of Sphyraena barracuda (Walbaum) {Sphyraenidae) ; Hamacreadium mutabile Linton, 1910 (Opecoelidae) , from the intestine of Ocyuriis chrysurus (Bloch) (Lutjani- dae) ; Haplosplanchnus {Schikhobalo- trema) acutus (Linton, 1910) (Haplos- planchnidae) , from the intestine of Abudefditf sa.iatilis (Linn.) ( Poma- centridae) ; Haplosplanchnus {Schik- hobalotrema) pomacentri Manter, 1937 (Haplosplanchnidae) , from the intes- tines of Pomacentriis leucostictus Miil- ler and Troschel, and P. planij tons (Cuv. and Val.) (Pomacentridae) ; Midtitestis chaetodoni Manter, 1947 (Lepocreadiidae) , from the intestines of Chaetodon capistiatus Linn, and C. ocellatus Bloch (Chaetodontidae) ; the metacercaria of Neoapocreadiuin colli ( Sog'andares, 1959) (Lepocreadiidae), encysted in crustacean muscle remains from the intestine of Halichoeres bi- ritattus (Bloch) (Labridae); Hurley- trematoides chaetodoni (Manter, 1942) (Monorchiidae) , from the intestines of Chaetodon capistratiis Linn., C. ocel- latus Bloch, and C. striatus Linn. (Chaetodontidae) ; Siphoderu rinaled- waidsi (Linton, 1901) (Cryptogonimi- dae), from the intestines of Lutjanus syiiagris (Linn.) and Ocynrus chrysur- us (Bloch) (Lutjanidae) ; and Thele- trum magnasacciim (this paper) (He- miuridae), from the stomach of Abii- defduf sa.vatilis (Linn.) (Pomacentri- dae). The systematic status, distribu- tion, hosts and new information on the morphology of each trematode species is discussed. TULANE STUDIES IN ZOOLOGY VOLUME 1, 1953-54 Number Price 1 On a new genus and species of mysid from Louisiana (Crustacea, Malacostraca ), by Albert H. Banner, pp. 1-8 (June I, 1053) . .$0.2o 2 A contribution on the life history of the lizard Scincella laterale (Say), by Richard M. Johnson, pp. 9-27 (July 3, 1953) 75 3 An outline for the study of a reptile life history, by Fred R. Cagle, pp. 29-52 (July 28, 1953) 75 4 A population of Ilolbrook's salamander, Eurucea longicauda guttolineata (Hol- brook), by Robert E. Gordon, pp. 53-60 (August 15, 1953) 25 5 A redescriptlon of the crawfish Procam- barun hinei (Ortmann) (Decapoda, Astaci- dae). by George Henry Penn. pp. 61-68 (September 1, 1953) 25 6 A new burrowing crawfish of the genus Procambarus from Louisiana and Missis- sippi (l»ecapoda. Astacidae), by George Henry Penn, pp. 69-76 (September 15, 1953) 25 7 The life history of fhe crawfish Orronectea (Faxonella) clppeatun (Hay) (Decapoda, Astacidae), by Elsie Wayne Smith, pp. 77- 96 (October 23, 1953) 50 8 Ostrincola oraciHs C. B. Wilson, a parasite of marine pelecypods in Louisiana (Cope- poda, Cyclopnida), by Arthur G. Humes, pp. 97-107 (December 21. 1953) 25 9 Hybrid inviabillty between h'ana pipiena from Wisconsin and Mexico, by B. Peter Volpe, pp. 109-123 (February 8, 1954) 35 10 The butterflies and skippers of Louisiana, by Edward Nelson Lambremont, pp. 125- 164 (April 30, 1954) 60 11 Two new species of the genus Orapteviya, by Fred R. Cagle. pp. 165-186 (August 26, 19.54) 75 12 The taxonomic status of the mid-Gulf Coast Amphiuma. by Tmoirene R. Hill, pp. 189-215 (August 26. 1954) 35 Complete volume, Including title page and table of contents, (unbound) $4.25 VOLUME 2, 1954-55 1 A new Eulimnadia from the rice fields of Arkansas with a key to the American species of the genus (Conchostraca, Llm- nadildae), by N. T. Mattox, pp. 1-10 (Sep- tember 14, 1954) $0.25 2 Studies In the ecology of the narrow- mouthed toad, Microhyla carolinenaia caro- linenaia, by Paul K. Anderson, pp. 13-46 (November 8, 1954) 50 3 A new species of Diaptomna from Louisi- ana and Texas with notes on the subgenus Leptodiaptomua (Copepoda, Calanoida). by Mildred Stratton Wilson, pp. 47-60 (No- vember 29, 1954) 25 4 Three new species and new records of southern millipeds. by Nell B. Causey, pp. 61-68 (December 28. 1954) 25 5 Notropia baileyi, a new cyprlnid fish from Pascagonla and Mobile Bay drainages of Mississippi and Alabama, bv Royal D. Suttkus and Edward C. Raney, pp. 69-86 < January 12. 1955^ .10 6 A reconsideration of the racer Coluhpr conatrictnr. In eastern United States, by Walter Auffenberg, pp. 87-155 (February 25, 1955) 1.00 VOLUME 2, 1954-55-Continued Number Price 7 Notropis hypsilepin. a new cyprlnid fish from the Apalachicola River system of Georgia and Alabama, by Royal D. Suttkus and Edward C. Raney, pp. 157-170 (Feb- ruary 25, 1955) 30 8 The fishes of two Gulf Coastal marsh areas of Florida, by John D. Kilby. pp. 171-247 (May 4, 1955) 1.00 Complete volume, including title page, table of contents and index (unbound) ... .$3.75 VOLUME 3, 1955-56 1 Notropia asperifrona, a new cyprlnid fish from the Mobile Bay drainage of Alabama and Georgia, with studies of related spe- cies, by Royal D. Suttkus and Edward C. Raney, pp. 1-33 (July 8, 1955) $0.50 2 A new Louisiana copepod related to Diap- tomua (Aglaodiaptoinua) claripea Schacht (Copepoda, Calanoida), bv Mildred Strat- ton Wilson, pp. 35-47 (August 1. 1955) ... .30 3 A new species of Sternotherua with a dis- cussion of the Sternotherua rarinatua com- plex (Chelonia, Kinosternidae), by Don- ald W. Tinkle and Robert G. Webb, pp. 51-67 (August 30, 1955) 50 4 A new Cambarus of the Dioaenea section from North Louisiana (Decapoda, Astaci- dae), by George Henry Penn, pp. 71-81 (September 30, 1955) 25 5 Hotropia euryzonua, a new cyprlnid fish from the Chattahoochee River system of Georjria and Alabama, bv Royal D. Suttkus, pp. 83-100 (December 28, 1955) 50 6 Factors Influencing the rate of oxygen con- sumption of the dwarf crawfish, Camba- rellua ahufeldtii (Decapoda Astacidae). by Milton Flngennan, pp. 101-116 (December 28. 1955 ) 35 7 Identification and geographical variation of the cyprinodont fishes Fundnlua oliva- ceua (Storer) and Fundulua notatua (Rafl- nesque), by Jerram L. Brown, pp. 117-134, (February 3, 1956) 50 8 The physiology of the melanophores of the isopod Idothea exotica, by Milton Finger- man, pp. 137 148 (April 12, 1956) 30 9 Osmotic behavior and bleeding of the oyster Crasaoatrea virginica, by Milton Fin- german and Laurence D. Fairbanks, pp. 149-168 (April 12. 1956) 50 10 Anatomy of the eyestalk of the white shrimp, Penaeua aetiferua (Linn. 1758). by Joseph H. Young, pp. 169-190 (June 22, 1956) 50 Complete volume. Including title page, ta- ble of contents and Index (unbound) $4.00 VOLUME 4, 1956 1 A study of the distribution and taxonomy of the percld fish Percinn niiirnfaaciata (Agassiz). bv Ronald W. Crawford, pp. 1- 55 (August 1. 195fi^ $0.75 2 Experimental F, hybrids between Riifo vnVicepa and Tiufn fntvlpri, by R. Peter Volpe, pp. 59-75 (September 30, 1956) 40 3 An outline for the study of an amphihinn life historv. bv Fred R. Cagle, pp. 77-110 (October 31. 1956) 40 4 Notes on habitats. «vstpmat1c obaracfprs and life histories of Teyas salt wnter Cvp- rlnodontes. bv Don O Simpson and Gordon Gunter, pp. 113-134 (December 31, 1956) .35 TULANE STUDIES IN ZOOLOGY VOLUME 4, 1956-Continued Number P""^^* 6 Dominance subordlnance relationshlpa In the crawfish Cainiarellus shufeldtii, by Mildred Eileen Lowe, pp. 137-170 (Decem- ber 31, 1956) 45 6 Propogation of the white shrimp, Penaeua aetiferus (Linn.) in captivity, by Malcolm C. Johnson and J. R. Fielding, pp. 1(3-190 (December 31. 1956) ^» Complete volume, including title page, ta- ble of contents and index (unbound) $J.&U VOLUME 6, 1958-Continued Number Price 4 The copepod genus Halicyclops in North America, with description of a new species from Lake Pontchartraln. Louisiana, and the Texas coast, by Mildred Stratton Wil- son, pp. 176-189 (December 31, 1958). Ontogeny of the first and second pleopods of the male crawfish Orconectea clypeatua (Hay) (Decapoda, Astacidae), by Joe B. Black, pp. 19()-203 (December 31, 1958) ... .60 Complete volume, including title page, table of contents and index (unbound) $3.50 VOLUME 5, 1957 1 Oambusia heterochir, a new poecillid fish from Texas, with an account of its hybrid- ization with O. affinis, by Clark Hubbs, pp. 1-16 (March 18, 1957) $0.30 2 New calanoid copepods of Pontella Dana and Labidocera Lubbock with notes on the distribution of the genera in the Gulf of Mexico, by Abraham Fleminger, pp. 17-34 (March IS, 1957) 30 3 Three new crayfishes from Alabama and Mississippi (Decapoda: Astacidae), by Hxjrton H. Hobbs. Jr. and Margaret Wal- ton, pp. 37 52 (March 18, 1957) 30 4 Heat death and associated weight loss of the oyster Craaaostrea virginica, by Milton Fingerman and Laurence D. Fairbanks, pp. 53-62 (April 1, 1957) 30 5 The Odonata of Louisiana, by George H. Blck, pp. 69-135 (May 15. 1957) 1.00 6 Endocrine control of the red and white chromatophores of the dwarf crawfish, Cambarellua ahufeldti, by Milton Finger- man, pp. 137-148 (June 7. 1957) 30 7 Hormones controlling the chromatophores of the dwarf crawfish, Cambarellus ahu- feldti : their secretion, stability, and sepa- ration bv filter paper electrophoresis, by Milton Flngerman and Mildred E. Lowe, pp. 149-171 (June 7. 1957) 40 8 Cyprinid fishes of the subgenus Cyprinella of Notropis. II L Variation and subspecies of Notropia venuatua (Girard), by Robert H. Glbba, Jr. pp. 173-203 (August 7, 1957) .50 9 The early development of Rana capita aevo- «o. by E. Peter Volpe, pp. 205-225 (Septem- ber 12, 1957) 35 11 The skeleton shrimps (Crustacea: Caprel- lldae) of the Gulf of Mexico, by Joan E. Steinberg and Ellsworth C. Dougherty, pp. 265-288 (December 80, 1957) 40 10 Variation and subspecies of the crawfish Orconectea palmeri (Faxon) ( Decapoda, Astacidae), by George Henry Penn, pp. 229-262 (September 12, 1957) 60 12 The systematic status of the suckers of the genus Moxostoma from Texas, New Mexico, and Mexico, by C. Richard Robins and Edward C. Raney, pp. 289-318 (Decem- ber 30. 1957) 45 Complete volume, Including title page, ta- ble of contents and Index (unbound) ....$5.00 VOLUME 6, 1958 1 The systematica and ecology of the Sterno- thaerua carinatua complex (Testudinata, Chelydrldae), by Donald W. Tinkle, pp. 1-56 (March 31, 1958) $1.25 2 The butterflies of Mississippi, by Bryant Mather and Katharine Mather, pp. 61-109 (June 6, 1958) 1.00 3 Aquatic and semlaquatlc Hemlptera of Mis- sissippi, by Clifton A. Wilson, pp. 113-170 (September 5, 1958) 1.00 VOLUME 7, 1959 1 An illustrated key to the crawfishea of Louisiana with a summary of their distri- bution within the State (Decapoda, Asta- cidae), by George Henry Penn, pp. 3-20 (April 23, 1959). Comparison of the chromatophorotroplns of two crayfishes with special reference to electrophoretlc behavior, by Milton Flnger- man, pp. 21-30 (April 23. 1959) $0.60 2 A review of the seabassea of the genus Centropriatea (Serranldae). by Rudolph J. Miller, pp. 33-68 (July 9, 1959) 75 3 Dlgenetlc trematodes of marine fishes from the Gulf of Panama and Bimlnl, British West Indies, by Franklin Sogandares-Ber- nal, pp. 69-117 (August 24, 1959) 1.00 4 Parasites of the commercial shrimps, Pen- aeua aztecua Ives, P. duorarum Burkenroad, and P. aetiferua (Linnaeus), by Dwayne Nathaniel Kruse, pp. 123-144 (October 19, 1959). The larva of the oak toad, Bufo quercicua Holbrook, by E. Peter Volpe and James L. Doble, pp. 145-152 (October 19, 1959) 60 Complete volume, including title page, table of contents and index (unbound) $2.65 VOLUME 8, 1960 1 Studies on the backswlmmers of Costa Rica (Hemiptera; Notonectidae), by John L. De Abate, pp. 1-28 (April 29, 1960) $0.60 2 Three Ascocotyle complex trematodes (Het- erophyldae) encysted in fishes from Louisi- ana, including the description of a new genus, by Franklin Sogandares-Bernal and John F. Bridgman, pp. 31-39 (October 28, 1960). Age and growth of the spot, Leiostomua xanthurua Lac^pSde, by Bangalore I. Sun- dararaj, pp. 41-62 (October 28, 1960) 0.65 dararaj, pp. 41-62 (October 28, 1960) 65 3 The breeding habits of the mole salaman- der, Ambystoma talpoideum (Holbrook), in southeastern Louisiana, by C. Robert Shoop, pp. 65-82 (December 2, 1960) Salinity relations of some fishes in the Aransas River, Texas, by William C. Ren- fro, pp. 83-91 (December 2, 1960) 50 4 Ecology of the rice rat, Oryzomys palustria (Harlan), on Breton Island, Gulf of Mexico, with a critique of the social stress theory, by Norman C. Negus, Edwin Gould, and Robert K. Chipman, pp. 93-123 (May 10, 1961) 60 Orders should be addressed to Meade Natural History Library, c/o Department of Zoology, Tulane University, New Orleans, 18, La., USA Please make remittance payable to "Tulane University" i KAR/ARD UNtVERSilY Volume 8, Number 6 July 14, 1961 THE FEMALE REPRODUCTIVE CYCLE OF THE CRAYFISH CAMBARELLUS SHUFELDTI: THE INFLUENCE OF ENVIRONMENTAL FACTORS MILDRED EILEEN LOWE, DEPARTMENT OF ZOOLOGY, LNIVERSITY OF MELBOURNE, MELBOURNE, AUSTRALIA FECUNDITY AND REPRODUCTION IN THE LARGESCALE MENHADEN, BREVOORTIA PATRONUS GOODE ROYAL D. SUTTKUS and BANGALORE I. SUNDARARAJ, DEPARTMENT OF ZOOLOGY, TULANE UNIVERSITY, NEW ORLEANS, LOUISIANA TULANE UNIVERSITY NEW ORLEANS TULANE STUDIES IN ZOOLOGY is devoted primarily to the zoology of the waters and adjacent land areas of the Gulf of Mexico and the Caribbean Sea. Each number is issued separately and contains an individual monographic study, or several minor studies. As volumes are completed, title pages and tables of contents are distributed to institutions ex- changing the entire series. Manuscripts submitted for publication are evaluated by the editor or associate editor and by an editorial committee selected for each paper. Contributors need not be mem- bers of the Tulane University faculty. The editors of Tulane Studies in Zoology recommend conformance with the principles stated in chapters I and II ( only ) of the Style Manual for Biological Journals published in i960 by the American Institute of Biological Sciences, Washington, D. C Manuscripts should be submitted on good paper, as original typewritten copy, double- spaced, and carefully corrected. Two carbon copies in addition to the original will help expedite editing and assure more rapid publication. An abstract not exceeding three percent of the length of the original article must accom- pany each manuscript submitted. This will be transmitted to Biological Abstracts and any other abstracting journal specified by the writer. Separate numbers or volumes may be purchased by individuals, but subscriptions are not accepted. Authors may obtain copies for personal use at cost. Address all communications concerning manuscripts and editorial matters to the editor; communications concerning exchanges, and orders for individual numbers to the Director, Meade Natural History Library. When citing this series authors are requested to use the following abbreviations: Tulane Stud. Zool. Price for this number: $0.60 Dr. Royal D. Suttkus, Director Meade Natural History Library Zoology Department Tulane University New Orleans 18, Louisiana U. S. A. Dr. George Henry Penn, Editor (on leave) Tulane Studies in Zoology Zoology Department Tulane University New Orleans 18, Louisiana U. S. A. Dr. Franklin Sogandares-Bernal, Acting Editor Tulane Studies in Zoology Zoology Department Tulane University New Orleans 18, Louisiana U. S. A. Dr. Charles F. Lytle, Associate Editor Tulane Studies in Zoology Zoology Department Tulape University New Orleans 18, Louisiana U. S. A. Mr. C. Robert Shoop, Assistant to the Editors Tulane Studies in Zoology Zoology Department Tulane University New Orleans 18, Louisiana U.S.A. JUL 2 6 1961 HARVARD UNIVERSITY TULANE STUDIES IN ZOOLOGY Volume 8, Number 6 July 14, 1961 CONTENTS THE FEMALE REPRODUCTIVE CYCLE OF THE CRAYFISH CAMBARELLUS SHUFELDTI: THE INFLUENCE OF ENVIRONMENTAL FACTORS Mildred Eileen Lowe 157 Editorial Committee: Dr. Horton H. Hobbs, Jr., Professor of Biology, University of Virginia, Charlottes- ville, Virginia Dr. George Henry Penn, Professor of Zoology, Tulane University, New Orleans, Louisiana Dr. Grover C. Stephens, Assistant Professor of Zoology, University of Minnesota, Minneapolis, Minnesota FECUNDITY AND REPRODUCTION IN THE LARGESCALE MENHADEN, BREVOORTIA PATRONUS GOODE Royal D. Suttkus and Bangalore I. Sundararaj 177 Editorial Committee: Dr. Edward C. Raney, Professor of Zoology, Cornell University, Ithaca, New York Dr. Earl E. Deubler, Jr., Associate Professor, Institute of Fisheries Research of the University of North Carolina, Morehead, City, North Carolina Dr. Gerald E. Gunning, Assistant Professor of Zoology, Tulane University, New Orleans, Louisiana THE FEMALE REPRODUCTIVE CYCLE OF THE CRAYFISH CAMBARELLUS SHUFELDTI: THE INFLUENCE OF ENVIRONMENTAL FACTORS ^ MILDRED EILEEN LOWE, Department of Zoology, University of Melbourne, Melbourne, Australia Many organisms show a reproductive pe- in the palolo worm, is believed to be ini- riodicity correlated with environmental fac- ated by increased photoperiod ( reviewed by tors. Photoperiodism and response to chang- Korringa, 1947). ing temperature are the best known phe- Among the Crustacea, G. J. Stephens nomena. Food and rainfall and, in marine (1952) showed, in Orconectes virilis. that organisms, changes in salinity and changes increased day-length accelerated the rate of in pressure due to spring tides, may also the normal cyclic increase and decrease in affect time of egg-laying. ovarian size. She also demonstrated that con- Most of the research on influence of pho- stant darkness completely interrupted cyclic toperiodism upon reproductive cycles in in- activity, the oocytes developing to a mature vertebrates concerns induction of diapause condition and remaining in that state. How- in insects. This subject was reviewed by ever, Suko (1958) showed that the response Lees (1955). Most insects may be classi- of Procambarus clarkii to darkness depends fied as "long-day" species; that is, exposure on the state of the ovary when the animal to long day-lengths allows uninterrupted de- is placed in the darkness. With another velopment while short day-lengths favor crayfish, Orconectes rusticus. G. C. Stephens diapause. However, in many insects ex- (1952) showed that light caused modifica- tremely short day-lengths or constant dark- tions of a secondary sexual structure, the ness may also prevent diapause. cement glands, which secrete a substance High temperatures augment the effect of used in attaching the newly-laid eggs to the long day-lengths in preventing diapause, pleopods. These glands were stimulated to while low temperatures favor its onset. For develop at a more rapid rate in animals the termination of diapause, temperature under increased photoperiods. may be more important than day-length as The present investigation was undertaken many insects require a period of chilling be- to define the female reproductive cycle of fore diapause terminates (Lees, 1955). the crayfish Cambarellus sbufeldti. This By increasing the temperature in mid- small crayfish is readily available in south- winter Loosanoff and Davis (1952) initiat- eastern Louisiana throughout the year. It ed a second breeding season in the oyster has been used in studies on chromatophores, Crassostrea virginica which normally breeds retinal pigment migration, metabolism, and only during the summer. Low temperature on the endocrine factors controlling these stimulated breeding in B^/d««j. while spawn- functions (e.g.. Fingerman, 1957; Finger- ing occurred both at time of maximum and ^nan and Lowe, 1957). The only studies of of mmimum temperatures in the limpet ^^^ uf^ ^y^e of this species were the brief Patella vulgata (Giese, 1959). ecological surveys of Penn (1942, 1950) Korringa (1952) showed that tempera- who reported an almost continual period of ture is not the only factor influencing reproduction with peak activity in late win- spawnmg. Withm the spawnmg season of ^^^^ continuing high through early summer, the European oyster, Ostrea edulis. semi- . r i • i i monthly peaks of reproductive activity are The series of observations presented here correlated with spring tides. In this and represents an attempt ( 1 ) to outline in de- other animals exhibiting increased activity tail the female reproductive cycle of this two times each lunar cycle, the increased crayfish, and ( 2 ) to obtain information con- water pressure of spring tides might be the cerning environmental factors that may reg- triggering influence. Monthly spawning, as ulate the cycle. 1 Most of this paper is a portion of a dissertation submitted in partial fulfilment of the requirements for the Ph.D. degree in zoology at Tulane University, New Orleans, Louisiana, 1959. 158 Tulane Studies in Zoology Vol. 8 Materials and Methods Adult specimens of Cambarellus shujeldti are small, the female averaging only 20 mm in length. Typically they inhabit shallow fresh-water ponds and ditches that are ex- posed to direct sunlight part of each day and that contain an abundant plant growth (Penn, 1942, 1950). The population stud- ied occurred in a roadside ditch, in pine- lands, near Pearl River, Louisiana. The prin- cipal water plants present were Scirpus na- nus and Rhyncospora spp. Other crayfishes associated with Cambarellus were Orconec- tes clypeatus and Procambarus blandingi acutus. The water level in the ditch fluctuated from approximately 18 inches to below ground level according to the amount of rainfall. Very little rain fell during late au- tumn of 1958 and the ditch was dry from the middle of December to the third week in January, 1959. The crayfish can survive such droughts by burrowing. They evident- ly do not burrow unless there is no stand- ing water as a small December collection was obtained from only one-half inch of water by raking through plant growth. At all other periods during the study the cray- fish were active and were obtained with dip- nets. Although a thin film of ice formed over the water surface in February, 1958, animals were still present in the water. Animals were collected at least once a month from November, 1957, through No- vember, 1959, preserved in Bouin's fixative, and stored in 70 percent ethyl alcohol. The weights and measurements presented below are those obtained from preserved crayfish. The animals were blotted and weighed to the nearest milligram. Cephalothorax length, from tip of rostrum to posterior margin of carapace, was measured to the nearest 0.5 mm with the aid of dividers and a stereo- scopic microscope. The degree of cement gland development and the presence or absence of a plug in the oviducts were noted. In C. shujeldti the ce- ment glands underlie the anterior portions of the second through sixth abdominal seg- ments at the junction of the sterna and pleura and the mid-ventral line along the strong transverse bar present in each ster- num. The glands extend into the protopo- dite and endopodite of eacli pleopod and into both the exopodite and endopodite of the uropods. The degree of cement gland development was determined according to the stages of G. C. Stephens { 1952) : stage 1. Numerous tiny, milky-white translucent, circular or subcircular spots appear in areas of future gland development; stage 2. The white areas enlarge and subcircular trans- parent areas appear within them; stage 3- The glands appear as translucent white lo- bate clusters surrounding the original white areas in an irregular manner; stage 4. The glands become opaque, milky-white and so filled with secretion that their lobate char- acter is difficult to distinguish. In Cambarellus the mid-ventral glands mature slowly and may still be in stage 2 or 3 when the lateral glands are in the fully developed stage 4. Therefore, the states of the two sets of glands were recorded sep- arately. A stage listed as 4.0, 2.0 would in- dicate that the lateral glands were at stage 4, the mid-ventral only at stage 2. After the specimens had been examined grossly their ovaries were removed. The ovary is Y-shaped with two anterior and one posterior lobes located immediately ven- tral to the heart; the anterior lobes curve dorsally around its anterior end. The ovi- ducts originate from the ventro-lateral sur- face of the ovary where the three lobes join. Camera lucida drawings were made of the ovaries before removal from the animal, with the crayfish held in a lateral and slight- ly dorsal position. The diameters of the largest oocytes in each ovary were measured to the nearest 0.01 mm with an ocular micrometer and the average diameter of the four largest was re- corded. Each ovary was weighed to the nearest 0.1 mg. after being touched to a piece of filter paper and placed in a dry, covered weighing bottle. The weight of any moisture remaining in the weighing bottle when the ovary was removed was subtracted from the previously recorded weight. Results and Discussion "I'he Normal Yearly Reproductive Cycle Animals were collected at least once a month from November, 1957, through No- vember, 1959, to determine the normal re- productive cycle. Only animals of 8.5 mm cephalothorax length and larger were con- sidered because only two mature animals smaller than this were found. No. 6 Lowe: Female Reproductive Cycle of Crayfish 159 A population of C. shufeldti has an al- cephalothorax length produces only a hazy most continuous period of reproductive ac- pattern of growth as seen in Table 2 which tivity. Females bearing eggs or young can summarizes the correspondence between be collected nearly every month of the year, weight and length throughout the study. The eggs are attached to the female's pleo- In January 1958 only one size group of pods, where young hatch from the eggs and adult females was present. The same group remain attached through the second instar. ( hereafter referred to as group A ) was The total time of attachment to the pleo- present in February, showing a small incre- pods in Cumbarellus is about three weeks. ment in weight and no increase in length. The percentage of females bearing eggs Eighty-five percent of these animals carried and young is shown in Figure 1. Two peaks eggs or young. The largest juveniles meas- of reproductive activity occur, the higher in ured 7.5 mm cephalothorax length; they late winter and a second in early summer, were not weighed. A small rise also occurs in October. By March many group A animals had The life cycle. — Approximately fifty fe- lost their young and molted, and the group males from each of the monthly collections showed a large weight increase. A second from January, 1958, through November, group of females (group B) had molted to 1959, were weighed and cephalothorax meas- mature size. These latter comprised 36 per- ured. Animals carrying eggs or young were cent of the adult female population and all weighed with brood attached. Each month were ovigerous. The largest juvenile meas- some animals were dissected to determine ured 7.5 mm cephalothorax length, ovarian condition. By April 1958 all remaining group B Comparison of total body weight ( Tables animals had undergone a maturation molt 1 and 2 ) shows three distinct groups of fe- as the largest juveniles measured only 6.0 grow, become translucent white and then mm cephalothorax length. Approximately males which appear and mature at different 50 percent of the group carried eggs or times during the year. There is a definite young. All of group A had completed a separation between the heaviest animals in post breeding molt. These two groups could one group and the lightest in a second, not be separated on the basis of length as heavier group present in the population at group A measured 9.0-10.5 mm cephalo- the same time. Comparison of increment in thorax length and group B, 10.0-11.5 mm. Table 1. Body weight increment in the three groups throughout the study. Month Group A Group B Group C 1-58 164-206 (190)='= 2-58 190-223 (203) 3-58 256-310 (284) 181-200 (190) 4-58 292-387 (340) 186-215 (192) 5-58 315 193-240 (215) 6-58 268-340 (299) 196-227 (212) 7-58 329-359 (341) 148-265 (197) 8-58 163-253 (199) 9-58 196-245 (221) 10-58 235-384 (274) 11-58 158-185 (172) 292-364 (311) 12-58 178-210 (196) 300-345 (327) 1-59 192-230 (210) 377-418 (393) 2-59 215-292 (251) 3-59 256-310 (284) 167-201 (185) 4-59 305-378 (337) 179-220 (200) 5-59 181-250 (220) 6-59 234-290 (278) 150-162 (156) 7-59 287-335 (310) 174-218 (194) 8-59 320-335 (330) 193-227 (211) 9-59 208-231 (218) 10-59 245-286 (265) 11-59 160-188 (175) 279-317 (299) * 164-206 = weie :ht range: (190) = mean. 160 Tulane Studies in Zoology Vol. 8 Table 2. Monihly weights and cephalothorax lengths of a representative sample of the adult female population. Month Group No. Measured & Weijrhed Cephalothorax Length (mm) range mean Weight (mg) range mean % in size class Jan. 1958 A 35 9.0-10.0 9.6 164-206 190 100 Feb. 1958 A 41 9.0-10.5 9.8 190-223 203 100 March 1958 A B 36 20 9.5-11.0 9.0- 9.5 10.0 9.2 256-310 181-200 284 190 64 36 April 1958 A B 19 28 10.0-11.5 9.0-10.5 10.5 9.7 292-387 186-215 340 192 40 60 May 1958 A B 1 42 10.5 9.0 10.5 9.8 315 193-240 215 2 98 June 1958 B C 46 15 9.0 11.5 9.0-10.0* 10.1 9.4 268-340 196-227 299 212 76 24 July 1958 B C 6 44 10.5-11.5 8.5-10.0 11.0 9.2 329-359 148-265 341 197 12 88 Aug. 1958 C 50 8.5-10.0 9.2 16.3-253 199 100 Sept. 1958 C 51 9.0-10.5 9.6 196-245 221 100 Oct. 1958 C 50 9.5-11.5 10.0 235-384 274 100 Nov. 1958 C A 52 13 9.5-11.5 9.0- 9.5* 10.2 9.2 292-364 158-185 311 172 so 20 Dec. 1958 C A 9 21 10.0 11.5 9.0-10.0 10.6 9.6 300-345 178 210 327 196 30 70 Jan. 1959 C A 4 45 10.011.5 9.5-10.5 11.0 10.0 .377-418 192-230 393 210 9 91 Feb. 1959 A 45 9.5-10.0 9.9 215-292 251 100 March 1959 A B 39 11 9.5-11.0 9.0- 9.5 10.1 9.2 265-315 167-201 288 ia5 78 22 April 1959 A B 24 31 10.0 11.5 9.0-10.0 10.6 9.« 305-.37S 179-220 337 200 44 56 May 1959 B 35 *9.0-10.5 9.7 181-250 220 100 June 1959 B C 48 4 9.5-11.0 *9.0-10.0 10.1 9.3 234-290 150-162 278 156 92 8 July T.t.".9 B C 14 36 10.5-11.5 8.5-10.0 10.8 9.2 287-335 174-218 310 194 28 72 Auk. 1959 B C 3 47 10.5-11.5 8.0-10.5 11.0 9.5 320-335 193-227 330 211 6 94 Sept. 1959 C 35 8.5-11.0 9.9 208-231 218 100 Oct. 1959 C 35 9.5-10.5 10.2 245-286 265 100 Nov. 19.59 ■IS it 10.0-11.5 8.5- 9.5 10.6 9.0 279 327 160-lSS 299 175 85 15 In these groujis 8.5 mm animals were present hut arc nut nK-liuicil in llic tahuhitii)ii as tlieir ovaries were in an immature condition. However, animals measuring 10.0 and 10.5 mm in group A were approximately 100 mg heavier than those of the same length in group B. Group A comprised only 2 percent of the population by May, 1958. Most group B individuals had lost the young from the pleopods but had not undergone a post- breeding molt. By June most of group B had molted and 65 percent of these had produced a second brood. A third group of females, group C, had begun to mature and formed 2 percent of the adult female population. Approximately 85 percent of this new group were ovigerous. The ovaries of 8.5 mm females that now appeared in the popula- tion were immature. In July the remainder of group B molted and all the animals were large, 10.5 to 11.5 mm cephalothorax length. This group com- prised 12 percent of the population and none was ovigerous. More group C animals had undergone a maturation molt and the No. 6 Lowe: Female Reproductive Cycle of Crayfish 161 ovaries of 8.5 mm animals reached a mature condition. Group C could be subdivided into two sections, the larger representing those animals hatched at the beginning of the winter breeding season and reproducing in June, the smaller those hatched towards the end of the season and reproducing in July and August. By August 1958 group B had disappeared from the population. The 18 percent of group C that carried eggs or young was composed of smaller animals, 8.5 to 9-0 mm. There were many juveniles whose cephalothorax length was 8.0 mm. The larger animals had shown no increase in weight. In September 1958 a number of the ani- mals molted as shown by increase in length, but the weight of the larger animals re- mained stationary. By October all the animals molted and there was a large weight increment. The largest animals produced a second brood. In November the larger animals of group C were dying off without molting again. The group made up 86 percent of the adult females as Group A began to appear in the adult population. The 8.5 mm animals possessed immature ovaries. Only in July and August were such small animals found in a reproductive phase. In December only a small collection could be obtained due to drought conditions. Group C constituted 30 percent of the adult female population. Some Group A animals had molted but the increment in weight was small. In late January, 1959, group C was com- posed of very large, heavy animals, all of which were ovigerous. Group A animals molted but had not yet laid eggs. By February the entire adult female pop- ulation was again composed of only one size group, group A, 63 percent of which were carrying eggs or young. Figure 1 and Tables 1 and 2 show the repetition of this cycle through the rest of 1959. Maturation of oocytes. — In the ovaries of immature animals the oocytes are tiny, 0.40 mm or less in diameter. They are transparent and widely separated by interstitial material. As the animals mature the oocytes begin to grow, become translucent white and then NDJFMAMJJASON MONTH COLLECTED Figure 1. The yearly reproductive cycle of C. shiifehlti expressed in terms of the per- centage of females that were carrying eggs or young. Solid line, circles = Nov. 1957- Nov. 1958; dotted line, dots = Nov. 1958 - Nov. 1959. 162 lulane Studies in Zoology Vol. 8 opaque ivory at approximately 0.70 mm in diameter. The oocytes later acquire a green- ish tinge as yolk deposition increases their size to 1.1 mm. The color of the oocytes gradually deepens to the dark dull green- black of mature eggs, with a diameter of 1.4 to 2.0 mm. Eggs are black immediately after laying. The smallest eggs found at- tached to the pleopods measured 1.45 mm. The same sequence of oocyte development is repeated after egg-laying occurs. At times yolk resorption occurs and the oocytes may become a bright chicken-yolk yellow or even orange. Oocytes undergo- ing resorption become coarsely granular, ir- regular vacuoles appear within them, and they become surrounded by a clear yellow fluid. When resorption is occurring rapid- ly the entire ovary may become distended with a pale yellow fluid. As resorption pro- ceeds the oocytes become smaller and their outlines irregular. They eventually disinte- J ■ J MONTH Fif^ure 2. Variation in mean ovarian weijjht thiouj^hout the year. Group A, Group B stippled; Group C solid bars. When two values are griven for the same in one month, the lesser value refers to animals carrying- eggs or young at time of urement. open ; group meas- No. 6 Lowe: Female Reproductive Cycle of Crayfish 163 grate leaving loose irregular masses of yel- low-orange granules that gradually disap- pear. Ovarian cycle. — The condition of the ovaries reflects the presence of the three size groups. Thus the ovarian weights of the Tables. Summary of monthly m,easurem.enifi on ovari-^n tveight and oocyte diameter. Month 1-58 2 58 3-58 4 58 5-58 6-58. 7-58 8-58 9-58 10-58 11-58 12-58 1-59 2-59 3-59 4-59 5-59 6 59 7-59 8-59 9 59 10-59 11-59 Group No. used Weigrht of Ovary (ins) rang-e mean Oocyte Diameter (mm) range mean A* A A- A* A*- B* A- A* T? B* A- B B B*- C. C* B C- C* c c* c c* c c- A C A c* A A* A A* A- B* A- B* B- B B B*- C B- C C* C&C- C* B- C C* c A 14 12 13 10 12 15 14 1 13 10 1 11 10 14 7 8 4 13 10 10 9 13 11 9 14 11 13 9 10 9 12 11 10 10 12 10 8 11 10 13 12 12 4 10 12 10 5 12 12 12 9 5.5- 8.2 18.7-20.3 7.2 19.5 13.2-17.3 1.7- 2.7 15.3 2.4 10.9-19.7 5.2- 5.6 11.8 5.4 13 9-15.6 9.2 7.4- 8.9 2.5- 3.7 14.6 8.1 3.1 21.0 9.1-16.9 13.2 30.9-32.1 9.812.0 16.2 19.5 3.8- 5.8 31.5 10,7 17.8 4.9 13.7-14.5 10.2-14.4 3.1- 5.8 14.0 32.1 4.5 6.0- 7.2 0.4- 0.7 6.7 0.5 0.7- 1.5 1.1 11.5-15.1 4.1- 6.5 13.2 5.0 16.0 18.7 6.0- 7.0 6.1- 7.8 17.5 6.5 7.0 17.0 19.4 7.2- 8.4 18.1 7.8 3.4- .3.8 9.3-12.8 3.6 10.9 1.2- i.8 28.0-29.3 1.5 28.6 4.8- 6.7 7.6 11.5 2.0- 3.5 .5.6 9.5 2.8 12.8-16.6 2 1- 3.1 6 9- 9.8 14.2 2.7 8.5 85-16.3 12.8 25.1-30.8 6.2-11.4 16.4-20.0 27.4 10.0 18.1 10.8-14.0 21.3-28.1 3.0- 5.5 12.6 23.2 4.6 6.7- 8.0 0.5- 2.0 8.0-10.1 7.3 1.2 9.0 0.7- 1.6 1.1 8.0-10.9 4.6- 5.0 9.3 4.8 12.8-15.8 6.7- 8.0 13.8 7.2 1.17-1.33 1.63-2.00 1.25 1.83 1.33-1..57 0.. 37 -0.67 1.51 0.49 0.92-1.16 0.58-0.68 0.98 0.64 0.85 0.98 0.83 0.69 0.98 0..58 0.67 0.92 0 89 0.63 1.25 0.84-1.18 1.04 1.67 0.84-1.08 1.34-1.68 0.66-0.92 1.67 0.98 1..50 0.81 1.46-1..51 1.. 35-1.. 53 0.50-0.82 1.48 1.41 0.68 1.10-1.18 0.38 0..50 1.15 0.41 0.35-0.66 0.44 1.25-1.43 0.75-0.83 1..34 0.79 1.25 1.43 0.78 0.92 1.23-1.33 1..35 0.85 1.28 1.48-1.60 1.26-1.34 1.53 1..30 0.80-0.85 1.33-1.67 0.&3 1.51 0..37-0..50 1.75-2.00 0.43 1.&5 0.65-0.83 0.87-1.14 0.58-0.71 0.74 0.96 0.65 0.84-0.99 O..57-0.fi7 0.75-0.96 0.91 0.64 0.87 0.87-1.20 1.05 1.63-1.68 0.79-1.04 1.40-1.61 1.65 0.91 1.51 1.40-1.47 1.51-1.73 0.47-0.79 1.44 1.63 0.64 0.98-1.18 0.43-0.58 1.20-1.31 1.04 0..51 1.24 0.37-0.61 0.48 1.15-1.23 0.68 0.74 1.18 0.71 1.20-1..38 1.16-1.31 1.28 1.23 * carrying eggs or young - had carried young recently, signs of egg cases still on pleopods 164 T/dane Studies in Zoology Vol. 8 three groups are plotted separately in Figure 2. However, in any one month the actual state of the ovaries of all non-ovigerous fe- males is rather similar regardless of group, the heavier animals having heavier ovaries mainly because the ovary contains a larger number of eggs rather than eggs in a more advanced state of maturation. Table 3 which lists oocyte diameter and ovarian weight by group shows this clearly (see April, Novem- ber ) . In most cases a single description in any one month will define ovarian condition in all non-ovigerous or in all ovigerous ani- mals at that time. Figures 2 and 3 illustrate the sequence of ovarian changes. January 1958. The ovaries of non-ovig- erous females (Fig. 3, A) were large, the oocytes mature. The posterior lobe of the ovary was almost three times the length of each anterior lobe. The anterior lobes were rounded and thick. They curved backward dorsally over the heart and pressed against the carapace. The ovary extended from the bases of the first pereiopods to the bases of the second pleopods. The ovary of breeding females averaged 7.2 mg and was growing (Table 3). February 1958. The ovaries of breeding Fi'jure ^. Annual cycle of ovarian development, January 1958 (3A) through February 1959 (3Q, R). See text for full explanation. No. 6 - Lowe: Female Reproductive Cycle of Crayfish 165 females were quite small and filled with in June when the ovary immediately began new oocytes (Fig. 3, C). Those animals not to increase in size and weight after egg- carrying a brood retained egg cases; young laying. The ovaries of those animals not had recently been present. The ovaries of carrying eggs or young averaged only 6.7 this group had doubled their weight (Table mg in weight and the oocytes were not uni- 3) and retained the same general shape as form but of various sizes (Fig. 3, K). Yolk present in January (Fig. 3, B). resorption was occurring; the ovary was re- March 1958. Group B had appeared and ducing in size, all were ovigerous. The animals of group September 1958. No females carried eggs A carried young or had molted after having or young. The ovary was small, 1.1 mg, a brood. About 5 percent of the oocytes and extended from the bases of the third present in recently molted animals showed to the fifth pereiopods. The oocytes were yolk resorption, accounting for the decrease round and of fairly uniform size; they were in ovarian weight. The posterior lobe of loosely arranged and one layer thick ( Fig. the ovary was more than twice the length 3, L), approximating the condition seen in of each anterior lobe (Fig. 3, D). The an- immature animals. terior lobes were elongated and narrow October 1958. Fifteen per cent of the rather than rounded and thick as in Jan- females carried eggs or young. The ovary uary and February. The ovary extended of these animals weighed 5 mg and was fromj the second pereiopods just to the first growing. In those animals not carrying a abdominal segment. brood the ovary averaged 13 mg in weight April 1958. The animals carrying eggs and oocytes measured 1.33 mm in diameter had small ovaries, filled with new oocytes. (Table 3). The ovary was thick and compact, The ovaries of the rest of the population extended from the second pereiopods to the had increased in size (Fig, 3, E) and were end of the thorax. The three lobes were of the same shape as in March. Within an of about equal size. The anterior ones were ovary the oocytes were not as uniform in upright with no backward curl (Fig. 3, M). size as previously; new oocytes were form- November 1958. Group A appeared in ing among more mature ones. the population. The oocytes in this group May 1958. Ovarian weight and oocyte underwent a slow maturation from Novem- diameter had increased ( Fig. 3, F ) . The ber to February when there was a sudden posterior lobe was approximately twice the increase in ovarian weight. In all females length of each anterior lobe. Only 5 per- present in November the posterior lobe of cent were brooding. the ovary was almost twice the length of June 1958. In animals carrying broods the anterior lobes; the anterior lobes were the ovary (Fig. 3, G) was larger as con- beginning to enlarge laterally (Fig. 3, N). trasted with comparable groups in Febru- December 1958. The ovary showed only ary, March and April, indicating a more a slight increase in weight over November, rapid maturation of oocytes after egg-laying. The posterior lobe had elongated to three In both ovigerous and non-ovigerous females times the length of the anterior ones. A the ovary was thick and compact, the pos- few young oocytes were apparent (Fig. terior lobe only one and one-half times the 3, O). length of each anterior lobe. January 1959. Ten percent of the females July 1958. Many of the non-ovigerous were ovigerous. They represented the rem- females still retained egg cases on their pie- nant of group C. The ovaries of the remain- opods. The anterior lobes of the ovary ing 90 percent had the same general shape were rounded and less than one-half the and extent as in December. While yolk length of the posterior lobe (Fig. 3, I). The deposition was occurring in the younger oocytes were larger than in June but had oocytes, resorption of yolk was beginning in not increased in number. some of the mature ones (Fig. 3, P). August 1958. The ovaries of brooding February 1959. In brooding females the animals were tiny, weighing only 0.5 mg ovary was small and thin, but compactly ar- and containing no oocytes larger than 0.42 ranged with little interstitial material (Fig. mm (Fig. 3, J). This condition contrasts 3. Q). The largest oocytes measured 0.5 with that occurring in specimens collected mm in diameter and represented old oocytes 166 Tulane Studies in Zoology Vol. 8 from which yolk was being resorbed. Small- er, new oocytes were being proliferated. In those females which had not yet laid eggs the ovaries approximated the condition found in January 1958, but was heavier. Yolk resorption was occurring in about 10 percent of the oocytes ( Fig. 3, R ) ■ This re- sorption was probably the result of forced retention of eggs past their maturation due to drought conditions at the end of 1958. Cement gland development. — Cement gland development parallels oocyte matura- tion. The glands are not apparent in imma- ture individuals. As the ovary approaches breeding condition the cement glands ap- proach their fullest development. They de- crease in size when egg-laying occurs and their secretion presumably provides the means of attaching eggs to the pleopods. After egg-laying the glands again begin to fill with secretion. Just as the ovary shows regression in late summer, so too do the cement glands, reducing to a stage of ap- proximately 0.5, 0.0 in September from stage 4.0, 3-5 in July (Table 4). The se- quence tabulated for 1958 also occurred during 1959. The presence or absence of an externally viewed plug in the oviducts is also recorded in Table 4. The significance of this plug is not known. It appears to be composed of an amorphous or granular white secretion, probably from the ovary itself. It is not present in immature animals or in mature animals in September, but is present to some extent throughout the rest of the year, becoming very prominent and causing the thin exoskeleton covering the oviduct open- ings to bulge outward prior to egg-laying. Even when not apparent externally this white material may be found in the upper part of the oviduct. It appears to move down the oviduct and before egg laying is present only in the lower part of the duct. The substance is particularly prominent in the upper part of the oviduct and even in the ovary itself, near the duct, when yolk resorption is occurring. Discussion. — The life span of female C. shufeldti is no longer than one year; that of an adult female, approximately six months, during which time she may pro- duce two broods. Those animals which hatch in the late winter-early spring breed- Table 4. Average monthly state of cement gland develomnent (fifty specimens were exatnined each month). Month Group A Group B Group C January 1958 2.0,0.0, slieht*- 4.0, 3.0, yes February 1958 3.5, 1.0, yes 2.0, 0.0, yes- March 195S 3.5, 2.0, yes 1.5, 0.0, slig'ht- April 1958 4.0, 2.0, yes 3.0, 2.0, yes 2.0, 0.0, yes- May 1958 4.0, 4.0, yes 3.5, 2.0, yes 4.0, 4.0, yes 4.0, 4.0, yes June 1958 3.0, ,0.0, , yes- 3.5, 0.0, yes- July 1958 4.0, 4.0, yes 3.0. 0.0, slight- 4.0, 3.5, slight Auffust 1958 0.5, 0.0, slight- 1.5. 0.0, shght September 1958 0.0, 0.0, no October 1958 3.0, 0.0, slight- 3.5, 2.0, yes November 195S 2.5, 0.0, no 3.5, 3.0, yes December 1958 3.0, 1.0, slight 4.0, 3.0, yes January 1959 4.0, 3.0, yes 2.0, 0.0, slight- February 1959 2.0, 0.0, slight- 4.0, 4.0, yes * The first number refers to stage of lateral cement glands, the second to stage of mid- ventral glands, "slight" refers to condition of oviducal plug, -carrying eggs or young No. 6 Lowe: Female Reproductive Cycle of Crayfish 167 ing season (group C) may mauire and be- Water was changed weekly; the animals come ovigerous at a small size in late June, were not fed during the course of the ex- July and August. In 1958 group C could periment. Illumination was provided in be subdivided into two parts: (1) those each tank by one frosted 10-watt bulb sus- animals hatched near the beginning of the pended 20 cm above the water surface, breeding season, and (2) those hatched Intensity of illumination at the surface of near the end of it. Due to drought con- the water was approximately 40-45 foot- ditions, the 1959 group C corresponded candles. Duration of light was controlled only to (2) of the 1958 group. The larger by automatic time clocks set to provide re- of the group C animals may have a second spectively 0, 6, 12, 18, and 24 hours of brood in October. A very few of the illumination daily. Illumination began at smaller group C animals may survive the 6 AM. uary. The June young (Group A) do not Beginning July 1 and every fifteen days winter and produce a second brood in Jan- until September 15 a random sample of attain sufficient size to reproduce until the animals was removed from each tank and following January and February. They re- preserved in Bouin's fixative for future ex- produce only once. The young produced amination. As both group B and group C in late July, August and October (group individuals were present during the early B) reach maturity and may produce young part of the experiment, the animals were in March and reproduce again in June. weighed and cephalothorax length measured The peaks of reproductive activity thus to separate the groups. The ovaries were produced are in fair agreement with those dissected out, weighed and largest oocyte published by Penn (1950) for C. shnfeldti. diameters measured. The results are sum- His data included animals collected through- marized by group in Tables 5 and 6. Stage out the state of Louisiana. As local condi- of cement gland development is also ra- tions vary, the expected flattening of the corded in these tables. curve occurs; the peaks he reports are not In group B animals, darkness caused an quite so high nor the dips so sharp. initial increase in ovarian size and this in- This is the shortest life cycle reported for crement was maintained through August 15, any crayfish; others studied have been those the last date on which animals of this group of larger animals that required a longer time were present in the population. Exposure to reach mamrity and lived longer in an to six-hour day-length also caused increase adult condition ( Hobbs, 1942; Penn, 194^; i" ovarian size but this was followed by a Smith, 1953). In these studies length was decrease in weight. For 12-, 18-, and 24- the only basis for separating different age hour day-lengths there was a decrease in classes. In C. shnfeldti at least, length alone ovarian weight. However, with 18 and 24 is not sufficient, as two distinct age groups, hours illumination daily this initial decrease clearly demarcated by weight, may have was followed by a weight increase, overlapping cephalothorax length measure- The same general sequence was shown by ments. Thus weight and length together animals of group C (Fig. 4). At the first must be used to define age groups accurate- sampling on July 1 these animals had just ly in this small shortlived species. molted to a mature size and there was an increase in ovarian size in 15 days under Influence of Environmental Factors all lighting conditions ( Fig. 4, B, H, N, T, Light. — To determine the effect of day- Z). A change from the situation in group length on the reproductive cycle, five groups B was that animals receiving a 12 -hour of crayfish were maintained under different photoperiod showed as great an increase as photoperiods from June 10 through Sep- caused by complete darkness. By August 1 tember 15, 1958. The animals were col- the ovarian weight of the animals in dark- lected on June 1, 4, 6, and 9, and not sep- ness was stabilized, while that of those arated as to collection date. Males and fe- under six-hour illumination showed an addi- males were present in each group. The tional increase, and the other groups a de- crayfish were contained in covered rectangu- crease. By the middle of August the ani- lar stainless steel tanks, 49 x 37 cm, kept mals receiving 18 to 24 hours of light daily side by side in an air-conditioned laboratory. (Fig. 4, V, BB) showed an increase in 168 Tulane St //dies in Zoology Vol. 8 Figure 4. Changes in ovarian condition of group C crayfish in response to different photoperiods. 0 hours illumination, A-F; 6 hours, G-L; 12 hours, M-R; 18 hours, S-X; 24 hours, Y-DD. ovarian weight while the others exhibited a least rapid in those under continual illumi- decrease. In both September samples groups nation. under all illuminations showed a decrease The cement glands generally followed the in ovarian weight, the most rapid decrease pattern shown by the ovaries ( Tables 5 and occurring in animals in darkness and the 6). However, the correlation was not per- Table 5. Changes in ovarian condition due to different photopei-iods : group B animals. Day- Length (Hrs.) Date Ovarian weight range mean Oocyte diameter range mean Cement gland stage No. of animals 0 7-1 7-15 8-1 8-15 11.5-13.9 13.1-15.6 13.0-14.9 13.2-14.7 12.5 14.0 13.8 13.9 1.50-1.75 1.50-1.81 1.50-1.70 1.48-1.55 1.68 1.70 1.60 1.51 2.5, 0.0, slight 2.5, 0.0, yes 3.5, 1.5, yes 3.0, 1.0, yes 9 8 5 5 6 7-1 7-15 8-1 10.5-12.5 10.9-13.0 7.7- 8.2 11.7 12.2 8.0 1.52-1.67 L50-1.73 1.28-1.36 1.60 1.60 1.32 2.5, 0.0, yes 3.0, 2.0, yes 2.0, 0.0, yes 8 6 4 12 7-1 7-15 8-1 10.5-11.9 9.7-10.8 7.9- 9.8 11.2 10.3 8.1 1.51-1.70 1.41-1.54 1.15-1.26 1.62 1.47 1.20 2.5, 0.0, yes 2.5, 0.0, yes 3.0, 1.0, yes 7 8 6 18 7-1 7-15 8-1 8-15 10.2-12.0 9.1-10.9 9.2-11.1 14.4-16.9 11.1 9.7 10.5 15.9 1.56-1.65 1.20-1.47 1.40-1.49 1.44-1.62 1.60 1.38 1.44 1.55 2.5, 0.0, yes 3.5, 2.0, yes 3.5, 2.0, yes 4.0, 1.0, slight 9 7 8 5 24 7-1 7-15 8-1 9.2-10.8 6.9- 7.9 8.5-10.7 10.1 7.6 9.5 1.50-1.59 1.19-1.25 1.30-1.39 1.55 1.22 1.35 2.5, 0.0. slight 2.5, 0.0, yes 3.0, 1.0, yes 5 6 7 No. 6 Lone: Female Reproductive Cycle of Crayfish 169 Table 6. Changes in ovarian condition due to different photoperiods : group C animals. Day- Ovarian weight Oocyte diameter Cement gland No. of Length Date range mean range mean stage animals (Hrs.) 0 7-1 2-1-3.8 3.2 0.85-0.91 0.91 2.5, 0.0, slight 6 7-15 6.G-7.8 7.2 1.13-1.40 1.30 2.5, 0.0, yes 7 8-1 6.0-7.9 6.9 1.26-1.40 1.33 3.5, 2.0, yes 8 8-15 6.0-7.8 6.7 1.26-1.43 1.34 3.0, 2.0, yes 6 1.9-2.1 2.0* 0.65-0.69 0.67 2 9-1 1.4-3.0 2.1 0.63-0.91 0.78 1.0, 0.0, no 10 9-15 0.7-1.2 0.9 0.35-0.43 0.38 0.0, 0.0, no 10 6 7-1 2.0-3.4 2.8 0.71-0.93 0.80 2.5, 0.0, slight 7 7-15 4.6-6.0 5.3 0.92-1.12 1.00 2.0,0.0, yes 9 8-1 6.4-7.8 7.1 1.21-1.42 1.31 3.0, 2.0, yes 8 8-15 3.9-5.7 4.9 0.67-0.91 0.81 1.5, 0.0, slight 7 9-1 1.0-2.2 1.6 0.35-0.53 0.43 0.5, 0.0, no 6 9-15 0.5-1.0 0.8 0.25-0.33 0.30 0.0, 0.0, no 5 12 7-1 2.0-3.0 2.4 0.60-0.71 0.66 2.0, 0.0, slight 8 7-15 6.0-8.4 7.4 1.31-1.56 1.40 3.5, 3.0, yes 7 8-1 5.0-6.1 5.6 0.89-1.06 0.97 3.5, 3.0, yes 8 8-15 2.8-3.5 3.2 0.81-0.97 0.89 3.5, 2.0, no 9 9-1 1.5-2.3 1.9 0.68-0.76 0.73 0.5, 0.0, no 6 9-15 0.3-0.9 0.5 0.21-0.30 0.25 0.0,0.0, no 10 18 7-1 1.9-3.3 2.4 0.42-0.75 0.60 2.5, 0.0, slight 6 7-15 5.2-6.4 5.9 0.98-1.08 1.04 3.5, 1.0, slight 7 8-1 3.4-4.5 3.7 0.87-0.98 0.93 3.0, 0.0, no 7 8-15 6.5-8.0 7.4 1.32-1.47 1.40 4.0, 4.0, yes 6 9-1 2.5-4.2 3.2 0.78-0.91 0.85 3.0, 1.0, slight 8 9-15 1.0-3.0 1.7 0.69-0.75 0.72 3.0, 1.5, slight 11 24 7-1 1.5-3.0 2.1 0.69-0.76 0.73 2.5, 0.0, slight 9 7-15 3.9-5.4 4.5 0.85-0.95 0.90 3.0, 0.0, yes 8 8-1 2.5-3.9 3.2 0.99-1.10 1.06 2.0, 0.0, yes 8 8-15 6.3-7.7 7.0 1.41-1.53 1.47 4.0, 4.0, yes 8 2.0-2.4 2.2* 0.85 0.85 2 9-1 3.2-5.0 4!l 1.06-1.17 1.12 3.0, 2.0, yes 9 9-15 1.1-3.0 2.0 0.72-0.84 0.78 3.0, 2.0, slight 10 ovigerous feet. In darkness there was a time lag in the maximum gland development and then the glands decreased while the ovarian weight remained steady. In group B ani- mals from July 1 to July 15 there was no decrease in cement gland stage although three of the groups showed decreased ovari- an weight and oocyte diameter. The longer the photoperiod, the greater the cement gland development; only under 18- and 24-hour day-lengths did the glands reach the fully mature 4.0, 4.0 condition. For approximately the same ovarian weight the glands of animals exposed to long day- lengths were more fully developed. The only animals to lay eggs during the course of the experiment were animals main- tained in constant darkness and in continual light. Two animals of each of these groups were ovigerous on August 15 (Table 5). While this fact is interesting the samples were not large enough to determine the sig- nificance of egg-laying by members of these two groups. Duration of light also had an effect on the ovaries of immature animals of 7.0, 7.5, and 8.0 mm cephalothorax length (Table 7 ) . These animals were present only in three tanks; 0, 12, and 18 hours light. Al- though these data are meager, the average representing never more than five animals, the greater ovarian maturation of those ex- posed to 18 hours illumination was very marked. There was a steady increase in ovarian maturity as exposure to long day- length continued and by September the 170 Tulane Studies in Zoology Vol. 8 Table 7. Average ovarian weights of immature animals exposed to 0, 12, and 18 hours light daily from June 10 to September 15, 1958. Date 0 hours Ovarian Oocyte weight diameter 12 hours Ovarian Oocyte weight diameter 18 hours Ovarian Oocyte weight diameter 7-1 .5 .20 .5 .20 .5 .20 7-15 8-1 .4 .5 .25** .25 .7 .5 .25* .20** .6 .9 .30 .43* 8-15 .5 .21* .4 .19 1.2 .69 9-1 .4 .20** .3 .13 2.0 .95 9-15 .4 .20 .3 .14** 2.4 1.06 * two animals only ** three animals only (The other measurements repi'esent four or five animals) oocytes had a diameter similar to that found in larger animals containing ovaries of 3 to 6 mg. A few crayfish of 6 mm cephalo- thorax length were present in the tanks, but ovaries of animals this small were indif- ferent to light conditions. They remained tiny, transparent threads containing minute oocytes. Cement gland development paralleled ovarian development. The glands of ani- mals in darkness and under 12 hours illu- mination remained undeveloped. Those un- der 18 hours illumination developed grad- ually to stage 3.0 (lateral glands), 1.0 ( mid- ventral glands) at the termination of the experiment. This degree of development was closely comparable to the stage 3.0, 1.5 of adult animals under the same conditions. This is in contrast to the results of G. C. Stephens (1952) who reported no increase in cement gland development in juvenile O. virilis subjected to long photoperiods. As the ovaries also remained in a juvenile con- dition, the animals used by Stephens might be comparable to the 6 mm C. sbufeldtt which were too young to respond. This effect of photoperiod may explain why the ovaries of animals measuring 8.5 mm cephalothorax length were found in a mature condition only in July and August; exposure to long day-length for a period of time may be necessary to bring them to maturity. However, natural day-length is not long enough to cause animals smaller than 8.5 mm to mature. A similar series of photoperiod experi- ments were undertaken beginning Septem- ber 30, 1959. At the beginning of the ex- periment all crayfish possessed undeveloped ovaries. The only crayfish to survive an unscheduled spraying with insecticide were nine of the animals in darkness. Four of these were sacrificed immediately. October 28, and the remainder on November 28. These results are included because the re- sponse of the crayfish to darkness differed from the response in the summer experi- ments. The ovaries did not develop ( Table 8. The small weight increase in November was due to proliferation of new oocytes and not to maturation. Temperature. — To determine the effect of Table S. Changes in ovarian condition due to darkness: placed in darkness September 30, 1959. Date Ovarian weight range mean Oocyte diameter range mean Darkness 10-28 11-28 0.9- 1.8- 2.9 5.3 2.0 3.4 0.35-0.62 0.33-0.65 0.47 0.48 Control (from Table 3) 9-15 0.7- 1.6 10-15 8.0-10.9 11-15 12.8-15.8 1.1 9.3 14.3 0.37-0.61 1.15-1.23 1.20-1.38 0.48 1.18 1.28 No. 6 Lowe: Female Reproductive Cycle of Crayfish 171 Table 9. Changes in ovarian condition due to different temperatures: placed at constant teTnperature November 5, 1958. Date Ovarian weight range mean Oocyte diameter range mean Cement gland development 5.5-7.5 °C. 11-22 11-29 12-6 12-20 1.4-2.8 1.9-4.5 2.5-6.1 6.3-8.5 2.1 2.8 4.0 7.4 0.60-0.74 0.67 0.60-0.95 0.81 0.67-1.00 0.82 1.06-1.28 1.20 1.0, 0.0, no 1.0, 1.0, no 3.0, 2.0, yes 3.0, 2.0, yes 14.5-19.5°C. 11-22 11-29 12-6 12-20 4.0-5.5 4.5-7.5 5.0-8.2 6.5-9.5 4.8 6.0 6.4 7.6 0.78-0.95 0.87 0.87-1.13 1.00 0.92-1.13 1.00 1.23-1.33 1.27 2.0, 0.5, no 2.5, 1.0, yes 2.5, 2.0, yes 3.0, 2.0, yes 29.5-30.5 °C. 11-22 11-29 12-6 12-20 4.6-6.7 1.4-5.5 0.8-2.1 0.3-1.2 5.6 3.3 1.5 0.8 1.24-1.30 1.27 0.58-1.07 0.81 0.43-0.83 0.65 0.17-0.53 0.33 2.5, 1.0, yes 2.0, 0.5, slight 1.0, 0.0, slight 1.0, 0.6, no temperature on the reproductive cycle of C. shufeldti, groups of crayfish were main- tained at 6.5 "C, 17°C, and 30 X for a period of one and one-half months. The same type tank and lighting arrangement as used in the light experiments was em- ployed. All groups received 12 hours light per day beginning at 6 AM. The 30 °C temperature was maintained by a hot water bath equipped with thermostat, the 17°C by a refrigerator, and the 6.5 °C by a con- stant temperature room. Variation in tem- perature was recorded by maximum-mini- mum thermometers. The mortality of the 6.5 °C group was initially high and then de- creased to a low level. Very few died in the other two groups. Both males and fe- males of groups B and C were present in each tank but only group C females were dissected. The animals were not fed during the course of the experiment. The ovaries were dissected in van Harre- veld's saline solution, which is isotonic to the blood of fresh water crustaceans ( van Harreveld, 1936). The ovaries were drawn in dorsal view. The wet weight of each ovary was recorded. However, as a con- stant amount of saline was not transferred with each ovary, they were later reweighed after preservation so these weights would be comparable to those of other experiments. Table 9 summarizes the sequence of ovarian changes under the three different temperatures and Figure 5 pictures ovarian condition. The animals were placed at constant temperature on November 5 and sampled at frequent intervals. At 17 ± 2.5 °C the ovarian development was similar to that of animals collected in the field. The ovaries from animals in the December 15, 1958, field collection averaged 7.8 mg and had an average oocyte diameter of 1.30 mm ( Table 3 ) while the experimental dis- sected December 20 averaged 7.6 mg with an oocyte diameter of 1.27 mm. The cooler temperature of 6.5 ± 1°C initially slowed development. However, the rate of development gradually increased so that by the end of the experiment the in- hibition due to cold had been overcome and the condition of these ovaries and that of the 17°C group was similar. Placing animals at an elevated tempera- ture, 30 ± 0.5 °C, caused a rapid increment in the ovarian size followed by deterioration with resorption of already formed oocytes and only limited proliferation of new ones. At reduced temperatures there was a con- tinual proliferation of new oocytes (Fig. 5, A-D) scattered among the maturing ones. At 17°C this proliferation was not so ap- parent (Fig. 5, E-H) and at 30"C the development of new oocytes was greatly slowed, the ovary being filled largely with a transparent interstitial material ( Fig. 5, I-L). The series of experiments with tempera- ture was repeated in February- April, 1959. 172 Tulane Studies tn Zoology Vol. 8 I M M r t- Figure 5. Sequence of changes in ovarian development under various temperatures. TQ, A-D; 17°C, E-H; 30°C, I-L. The low temperature was raised to 8.75 ± 1.25 °C to lower the mortality that oc- curred at 6.5°. The high temperature was 28.75 ± 0.25 °C rather than 30 ± 0.5 "C. Only group A animals that were ovigerous at the start of the experiment were used. To minimize the possibility of the animals at higher temperatures resorbing the ovary as a food source because of their higher metabolic rate, strands of Elodea were placed in the tanks and some canned cat food added every other day. Even with what was assumed to be an abundant food supply, the experimental re- sults (Table 10 j were essentially similar to those previously reported; a slowing of de- velopment at low temperatures and a sud- den increase followed by resorption at high temperatures. However, the lag in ovarian development at low temperature increased with time rather than decreased. Also, the regression at a higher temperature proceeded at a slower rate and interstitial material did not replace the oocytes to as great an extent. In the winter experiment cement gland development closely paralleled ovarian de- velopment, increasing or decreasing with ovarian development (Table 9). In the spring, however, cold temperature did not inhibit gland development; the glands of animals exposed to temperatures of 9°C were as fully developed as those of animals at 17°C (Table 10). The glands of animals at 29 "^C remained almost stationary at stage 3.0, 0.0. Temperature affected the development of attached eggs and developing young. All animals carried eggs in which little devel- opment was apparent at the start of the 1959 experiment. At 29 C only two ani- mals carried young at the time of the first sampling (18 days after the experiments be- gan). The rest exhibited only empty egg cases because the young had already left the No. 6 Lowe: Female Reproductive Cycle of Crayfish 173 Table 10. Changes in orarian condition due to different temperatures : placed at constant teynperature February 28, 1959. Ova rian weight Oocyte diameter Cement gland Date range mean range mean stage 28.5-29.0 °C. 3-17 2.4- 2.9 2.7 0.55-0.74 0.65 3.5, 0.0, yes 3-25 2.5- 4.9 3.9 0.67-0.80 0.73 4.0, 2.0, yes 4-1 3.7- 5.6 4.8 0.87-0.97 0.93 4.0, 3.0, yes 4-10 4.8- 5.6 5.2 0.87-0.98 0.94 4.0, 2.0, yes 16-19 °C. 3-17 1.7- 3.4 2.5 0.48-0.67 0.53 2.5, 0.0, slight 3-25 4.1- 5.6 4.9 0.76-0.87 0.81 3.5, 1.0, yes 4-1 6.5- 7.5 7.1 0.90-1.06 0.97 3.5, 1.0, yes 4-10 11.9-13.7 12.8 1.06-1.23 1.12 4.0, 2.0, yes 7.5-10.0°C. 3-17 3.8- 7.4 5.4 0.87-1.20 1.08 3.0, 0.0, yes 3-25 3.0- 6.8 4.7 0.83-1.20 0.97 3.0, 0.0, yes 4-1 3.0- 5.0 4.0 0.67-0.95 0.80 3.0, 0.0, yes 4-10 2.8- 3.6 3.2 0.71-0.85 0.78 2.5, 0.0, slight pleopods. At 17 °C, development was slow- er and a few young were still present on the pleopods after 22 days. A temperature of 9^C greatly slowed development; eggs were still present at the termination of the experiment, a total of 42 days. A few of these animals were then returned to room temperature and many of the eggs hatched in a few days. Discussion. — Temperature, duration of D S 0 JFMAMJJASONDJF '58 '59 MONTH Figure 6. Annual variation in temperature at Slidell, La., expressed in terms of mean monthly temperature. The solid bars at the base of the figure indicate the period during which 60 percent or more of the females were brooding. The vertical line through each bar indicates the peak reproductive period. 174 Tulane Studies in Zoology Vol. 8 light, and rainfall influence the reproductive cycle of CavihareUus sbi/feldti. The peaks of reproductive activity occur ( 1 ) in the coldest portion of the year, slightly after the shortest day-length, and ( 2 ) at the be- ginning of the hottest season which is also the time of longest day-length. Figure 6 shows the variation in mean monthly tem- perature throughout the year in the vicin- ity of the collection site. As the U. S. Weather Bureau does not maintain a tem- perature station at Pearl River, the temper- atures recorded are from Slidell, Louisiana, eight miles southwest of the collection area. Figure 7 gives the variation in day-length throughout the year at New Orleans, Louisi- ana, 26 miles southwest of the collection site and at sea level rather than 29 feet elevation. The times during which 60 per- cent or more of the adult female popula- tion carried eggs or young are indicated by the horizontal bars on the figures. The decreasing temperatures and shorten- ing day-lengths of late fall and early winter stimulate proliferation of new oocytes and inhibit ovarian maturation. Short days tend to stabilize the oocytes as they develop rather than allow the quicker cycling of yolk deposition and resorption induced by long photoperiods. Gradually the inhibi- tion induced by cold weather and short day length is lost, the ovaries mature and egg laying occurs. As temperature is rapidly increasing to- ward the summer plateau, the young of the year grow and mature quickly. The ovaries of adult animals develop rapidly and there is a sharp peak of reproductive activity in June. Long day-lengths accelerate the cyclic activity of the ovary. While the ovary in June and July grows very quickly after expelling eggs, contin- ued high temperature induces yolk resorp- tion and the ovaries regress until Septem- ber, when they approximate the condition seen in immature animals. Day-length has been increasing from March through June and smaller animals are finally stimulated to mature and lay eggs in July and August before their ovaries also regress. The strong inherent tendency for the late summer de- cline is shown by the series of experiments with day-length.. The ovary regressed un- der all illuminations in September. That this may be associated with a general meta- bolic factor is shown by the fact that ani- mals collected from the field in August and September exhibited less in body weight in- crease than in any other months during the year. As cooler weather and shorter photope- riods set in, the ovaries begin to grow again, new oocytes are proliferated and a few ani- mals are able to lay eggs before colder weather slows maturation of oocytes. The June young do not reach maturity before cold weather begins and are not able to re- produce until the following year. DJFMAMJJASO NDJFMAMJJASON ^^ MONTH ^^ Figure 7. Annual variation in photoperiod at New Orleans, La., expressed as month- ly mean number of hours from sunrise to sunset. The solid bars at the base of the figure indicate the period during which 60 percent or more of the females were brooding. The vertical line through each bar indicates the peak reproductive period. No. 6 Lowe: Female Reproductive Cycle of Crayfish 175 Rainfall can influence the reproductive cycle to the extent that animals may be forced to burrow if rainfall is scanty. This occurred in December 1958 - January, 1959. The forced burrowing of the crayfish placed them in complete darkness and may give an extra spurt to ovarian development. The combination of cold and darkness, plus forced retention of the oocytes may account for the large size reached by the ovaries before the animals laid eggs in 1959. Temperature has another effect on the reproductive cycle. Reproductive activity throughout the year was determined by the percentage of females carrying eggs or young. The time required for the eggs to hatch and for the young to leave the pleo- pods is inversely related to temperature. Mean monthly temperatures may vary from year to year and were lower during the 1958 winter breeding season than in 1959 so that, in effect, the period of peak reproduc- tive activity was extended in 1958. Lack of rainfall augmented the tempera- ture effect in 1958-1959 by forcing the animals to burrow and thus delayed their breeding season. By the time standing wa- ter was again present, temperatures were warmer and the time required for the young to develop shorter; thus shortening further the span of the reproductive peak in 1959. The data presented here agree with that of G. J. Stephens (1952) and Suko (1958). Stephen's experiments revealed that dark- ness stimulated maturation of oocytes and may inhibit cyclic activity, while increased light accelerated the cycle. Suko reported that oocytes of Procamharus clarkti kept in darkness for two to three months after ovi- position displayed no histological change in spite of the elongation of their ovaries ( in- dicating oocyte proliferation without ma- turation ) . Ovaries of animals kept further over this period developed earlier than those of controls. Animals kept in darkness im- mediately before breeding and egg-laying showed degenerative changes in the ovary. C shufeldti in the present experiments also showed varied response to lack of light depending on the time of year. Further experiments on the effects of light are needed. Also in the present ex- periments, there was little difference be- tween ovaries of animals exposed to 18 or 24 hours of light. The greatest day-length in New Orleans is 14 hours. How much the photoperiod can be reduced before dis- tinct differences appear would be interest- ing to determine. Summary 1. The reproductive cycle of the female dwarf crayfish, Cambarellus shufeldti. is de- fined. While females carrying eggs on their pleopods can be found almost any time throughout the year, there are two peaks of reproductive activity, the largest in late winter-early spring, the other in June. 2. Three distinct groups of adult females appear in the population during the year. Individual crayfish probably live no longer than a year and no longer than six months as adults. During this time an animal may reproduce twice. 3. Increase of photoperiod induces a more rapid cycling of the maturation and resorption of oocytes. Decrease of day- length tends to stabilize the ovary in a mature condition at one time of year, while at another time tends to allow increased proliferation of oocytes without maturation. 4. Lowered temperature tends to slow maturation of oocytes while elevated tem- peratures cause a quick maturation followed by disintegration of the ovary. 5. C. shufeldti appears to have an in- herent rhythm of reproductive activity, as shown by varied response to experimental lighting and temperature conditions at dif- ferent times during the year. References Cited FiNGERMAN, MiLTON 1957. Regulation of the distal retinal pigment of the dwarf crayfish, Cambarellus shufeldti. Jour. Cell, and Comp. Physiol., 50: 357-370. and Mildred E. Lowe 1957. Hormones controlling the chromat- ophores of the dwarf crayfish, Catn- barellus shufeldti: their secretion, sta- bility and separation by filter paper elec- trophoresis. Tulane Sttid. ZooL, 15(7): 151-171. GiESE, Arthur C. 1959. Annual reproduc- tive cycles of marine invertebrates. Ann. Rev. Physiol., 21: 547-576. HOBBS, HORTON H. Jr. 1942. The crayfishes of Florida. Univ. Fla. Pnbl., Biol. Sci. Ser., 3: 1-179. KoRRiNGA, P. 1947. Relations between the moon and periodicity in the breeding of marine animals. EcoL Monogr., 17: 347- 381. 1952. Recent advances in 176 Tulane Studies in Zoology Vol. 8 oyster biology. Quart. Rev. Biol., 27: 266-308, 339-365. Lees, A. D. 1955. The Physiology of Dia. pause in Arthopods. Cambridge Univ. Press, 150 pp. LoosANOFF, V. L. and H. C. Davis 1952. Repeated semi-annual spawning of north- ern oysters. Science, 115: 675-76. Penn, George Henry 1942. Observations on the biology of the dwarf crawfish, Camharellus shufeldti (Faxon). Amer. Midi. Xat., 28: 644-647. 1943. A study of the life history of the Louisiana red ciawfish, CambarKS clarkii Girard. Ecology, 24: 1-18. 1950. The genus Cam- barellns in Louisiana. Amer. Midi. Nat., 44: 421-426. Smith, Elsie Wayne 1953. The life his- tory of the crawfish Orconectes (Faxon- ella) clypeatus (Hay). Tidane Stud. Zool., 1: 77-96. Stephens, Grover C. 1952. The control of cement gland development in the cray- fish Cawhurus. Biol. Bull., 103: 242-258. Stephens, Gwen J. 1952. Mechanisms reg- ulating the reproductive cycle in the cray- fish Caiubaru.^. I. The female cycle. Fltys- iol. Zool, -Ih: 70-83. SuKO, Tetsuya 1958. Studies on the de- velopment of the crayfish. V. The his- tological changes of the developmental ovaries influenced by the condition of darkness. Sci. Rept. Saitama Univ., B- 3(1) : 67-78. Van Harreveld, A. 1936. A physiological solution for freshwater crustaceans. Proc. Soc. Exper. Biol. Med., 34: 428-432. Abstract The reproductive cycle of the female crayfish Cautbarellus shufeldti was de- fined. Field collections were made at least once a month from November 1957 through November 1959. While females carrying eggs on their pleo- pods could be found almost any time throughout the year, there were two peaks of reproductive activity, the largest in late winter-early spring, the second in June-July. These periods oc- curred shortly after the coldest por- tion of the year and shortest day- length and at the beginning of the hot- test portion which is also the time of longest day-length. Three distinct groups of adult fe- males appeared in the population dur- ing the year as determined by total body weight and cephalothorax length. Individual crayfish probably lived no longer than a year and no longer than six months as adults. During this time an animal could reproduce twice. Under incz'eased photoperiod a more rapid cycling of maturation and re- sorption of oocytes occurred. Decreased day-length tended to stabilize the ovary in a mature condition or to allow in- creased proliferation of oocytes with- out maturation, depending on time of year. Lowered temperature tended to slow maturation of oocytes while at elevat- ed temperatures there was quick matu- ration followed by disintegration of the ovary. FECUNDITY AND REPRODUCTION IN THE LARGESCALE MENHADEN, BREVOORTIA PATRONUS GOODE ^ ROYAL D. SUTTKUS and BANGALORE I. SUNDARARAJ, Depariment of Zoology, Tulane University, New Orleans, Louisiana Introduction There are no published accounts of obser- vations on spawning of the largescale men- haden. Suttkus (1956) estimated that spawning occurred between October and February in the Louisiana area. The assump- tion was based on examination of a number of gonads during different seasons and by extrapolation and interpretation of length- frequency tabulations (Suttkus, 1956). In late fall schools of menhaden move to inter- mediate depths prior to spawning. This movement in the late fall is common knowl- edge to menhaden fishermen along the Lou- isiana coast. Moreover, waters off the mouth of the Mississippi River, where menhaden concentrate, are turbid most of the time, perhaps in part accounting for lack of ob- servations on spawning. Materials and Methods The 280 specimens used in this study were obtained between 1951 and 1958 along the east Louisiana coast. Most specimens were obtained by otter trawls. Age Determinations Total length was measured from the an- terior tip of snout to tip of the lower caudal fin lobe. Standard length was measured from tip of snout to posterior margin of hypural; the latter point was determined by flexing the caudal fin. A scale sample was removed from the lateral area just above the tip of the ap- pressed left pectoral fin of each fish. Each scale was read three times with the aid of a Bausch and Lomb microprojector. Fecundity Most specimens were preserved in 10 percent formalin soon after capture and gonads were removed from specimens in the laboratory. Some gonads were removed from the specimens in the fresh condition, the volume was determined, and they were pre- served in 10 percent formalin. These gonads were remeasured after preservation; thus volumetric statistics are consistent. The maximum volume of the gonads was reached in January ( Figures 1 and 2 ) . Fecundity of the January specimens was determined by the volumetric method ( Lag- ler, 1956) as follows: (1) the total volume in cubic centimeters of each ovary was de- termined after removal of excess moisture; ( 2 ) a small piece was removed from the middle portion of the ovary. The excess moisture was removed and the volume de- termined; (3) the number of large eggs in this piece was counted under a stereoscopic binocular microscope; and (4) the total number of large eggs in the entire ovary was determined by proportion. To estimate the extent of error in the above method, actual total counts of large eggs were made of ovaries of age groups I and II. Results Age The scale method was used for determi- nation of age after consideration of the findings of June and Roithmayr (I960). Table 1 shows a total-length frequency tabu- lation by age groups for two samples of menhaden which were collected on January 30 and 31, 1958. These specimens were obtained with a mid-water trawl from the Gulf of Mexico, latitude 29° 21'N, longi- tude 88" 55'W. We assume the two samples were part of a spawning group. The con- dition of the gonads (Figures 1, 2, and 3) is substantiating evidence. No age group IV individuals were present in the two Janu- ary samples; however, 3 of the 280 speci- mens used in this study were of age group IV. Fecundity Fecundity data determined by volumetric method and by actual count are presented in Table 2. The average percent error for two ovaries is 5.5. Partially supported by NIH RG-6279(RI), NSF G-3882 and NSF G-9026. 178 Tulane Studies in Zoology Vol. 8 a u II.O - 10.0 - 9.0 - 8.0 - % 7.0 h z o » 6.0 u. o 34.0 > 3.0 2.0 I .0 (44) O - OVARY • - TESTIS L (t) (3) (I) -9 9(1) JUL AUG SEP OCT NOV DEC JAN FEB , MAR APR MAY JUN Figure 1. Mean volume of gonads of the largescale menhacj^fen for various months for ag-e groups I, II, and III. Figures in parentheses indicate nuihber of specimens. (Based on collections of menhaden obtained in 1951 thi'ough 1958.) The mean fecundity, total length, standard length, and volume of ovary, for various groups are shown in Table 3. The results show that fecundity increased with age and length. Reproduction Figures 1, 2, and 3 are based on composite samples obtained during the period 1951-58. There probably are slight fluctuations in the time of the spawning peak, from one year to the next as indicated by Suttkus ( 1956) on the basis of length-frequency tabulations. Moreover, the January peak shown in Fig- ures 1, 2, and 3 is at the time of year dur- ing which spawning was estimated to oc- cur. Apparently the enlargement of the gonads in preparation for spawning occurred during late fall, and spawning was finislied during February and or March. The illus- trations in Figure 4 show the typical ovaries of age groups I, II and III (bottom to top respectively) during the months of August (left), January (middle), and March (riglit). The great reduction in volume of the spent ovaries is obvious by comparison of photos taken in January and March. The firm Table 1. Toial length distribution of age groups of tivo samples of largescale menhaden col- lected on January 30 and SI, 1958 Length interval Age group in millimeters I II III 170-174 1 175-179 2 — 180-184 2 185-189 1 1 190-194 1 8 195-199 1 12 — 200-204 21 1 205-209 15 210-214 13 215-219 — 3 220-224 — 2 225-229 230-234 — 1 Number of fish 8 73 4 Percentage of total 9.4 85.9 4.5 Mean total length 182.6 202.7 219.5 No. 6 Suttkus and Sundararaj: Largescale Menhaden 179 13.0 12.0 - II. 0 - 10.0 - o 9 0 - - 8.0 h >- ^70 1- O 6,0 - 5 5 0 _j o > 4.0 3.0 - 2.0 A - Ar,e GROUP I • = AGE GROUP H O » AGE GROUP HI (I) JUL AUG SEP 1 1 1 OCT NOV DEC (1) -O JAN FEB MAR APR MAY JUN Figure 2. Mean volume of ovaries of largescale menhaden for various months for age groups I, II, and III. Figures in parenthese.? indicate the number of specimens. (Based on collections of menhaden obtained in 1951 through 1958.) Table 2. Comparisons of estimated and actual fecundities in the largescale menhaden Total length Volume of Estimated Actual Date Age in gonad number of number of Percent collected group millimeters in cc. eggs eggs error January 1958 31 I 176 4.0 21,960 20,827 5.4 January 1958 30 II 208 10.0 36,000 34,059 5.6 Table 3. Mean fecundity of 18 largescale unenhaden collected in January, 1958 Age group Number of specimens Mean total length in millimeters Mean volume of ovary in cc. Mean number of eggs per female I II III 2 14 2 176 209 228 4.0 12.7 17.2 21,960 68,655 122,062 180 Tulane Studies in Zoology Vol. 8 u CO LlJ o UJ Zi 70 6 0 5 0 4 0 3 0 % 2 0 0 - A - AGE GROUP I • ' AGE GROUP H O = AGE GROUP m (2) •(!) (I) JUL AUG ■ SEP ' OCT ' NOV ' DEC ' JAN " FEB " MAR ' APR ' MAY JUN Figure 3. Mean volume of testes of the larg-escale menhaden for various months for age groups I, II, and III. Figures in parentheses indicate the number of specimens. (Based on collections of menhaden obtained in 1951 through 1958.) texture and highly vascularized condition of the ovaries of those taken in January are also indicative of an ovary that is close to being spawned. The ovaries of the March samples were flaccid and the vascularization was degenerate. Age group II females of the January sample had an average gonad volume of slightly over 11 cubic centimeters whereas age group II males of the same sample averaged about 7 cubic centimeters. Part of the difference in volume is due to actual difference in volume of gonads of the same size individuals, though part is also due to the larger average size of the age group II females (Figure 5). The January 30 and 31, 1958, combined sample was the only one that was of suf- ficient size to warrant analysis of age com- position. In this .sample age group II in- dividuals made up 85 percent of the spawn- ing population, age group I made up ap- proximately 9 percent, and age group III about 4 percent ( Table 1 ) . Perhaps the most significant fact is that the largescale menhaden is a rapidly renewable resource. Acknowledgment We gratefully acknowledge the aid given by the following persons: Stewart Springer and Harvey Bullis, United States Fish and Wildlife Service, for furnishing specimens taken by trawl off the mouth of the Mis- sissippi River and to Robert Lee Eddy, Jr., formerly Chief of the Commercial Seafoods Division, Louisiana Wildlife and Fisheries Commission, for obtaining many of the samples. Literature Cited June, Fred C. and Charles M. Roithmayr 1960. Determining age of Atlantic men- haden from their scales. IJ . S. Fish & U'ilcU. Serv., Fish. Bull., 60(171) : 323-42. Lagler, K. F. 1956. Freshwater Fishery Biology. Wm. C. Brown Co., Dubuque, Iowa, 421 pp. SuTTKUS, Royal D. 1956. Early life history of the largescale menhaden, Brevoortia jHitnniKs, in Ix)uisiana. Trans. 21st N. A. Wildlife Co)if.: 390-407. Abstract Fecundity of the largescale menhaden, Brevoortia patron ks, from Louisiana coastal waters was estimated by volu- No. 6 Suttkus and Sundararaj: Largescale Menhaden 181 225-176 0.6 224-172 14.5 230-179 5.0 V 205-157 0.4 213-163 II. 0 209-161 3.0 <./ 176-136 0.2 iiiiiiiiiiii!iiiiiiiii;iiiili!i!|!iii!ipffliiiii!iiiim V :/ 176-136 4.0 180- 139 0.5 6| I TJ ' Sj 1 ^ m lllj !l2| Il3| 'Wj IISJ 1161 '"I 'l8| 'l9l '20, .!!, Figure 4. Ovaries of the largescale menhaden from age groups I, II, and III collected during August, January and March. Age group I (bottom row); age group II (middle row); and age group III (upper row). August sample (left column); January sample (middle column); and March sample (right column). The numbers separated by a hy- phen are the total and standard lengths of the specimens and that below is the volume in cubic centimeters for the particular ovary illustrated. 182 Tulane Studies in Zoology Vol. 8 20 0 - • • O = ■S -% (3)o 18 0 — o o 16 0 - o u o z o o o ^" o 0(3) ° 14 0 - o z o o 0(3) o o o li. 12.0 - oo o o o o o o llJ ° (1) o o s o o 5 10 0 - o o O ( D o • o o» > o • o • • • 8 0 • o • • • • • • • • • • •• • • o • 6 0 (1) (1) • (1) • • • (1) • • • • • • • • • • (3) • o • 4 0 • 1 1 1 1 1 175 185 195 205 215 TOTAL LENGTH IN mm. 225 235 Figure 5. Relationship between total length and volume of gonad, based on part of two samples of the largescale menhaden collected on January 30 and 31, 1958. All menhaden except where otherwise noted on figure were age group II. metric method. By actual count, we found 20,827 and 34,059 large eggs in the ovaries of one each of age groups I and II. Ovaries of age group II in- dividuals averaged about four cubic centimeters more than the testes of the age group II males from the same spawning mass. Part of the difference in gonad volume was due to the larger average size of the age group II fe- males. The period of the maximum vol- ume of testes and ovaries in addition to texture indicate a spawning peak in January. Age group II individuals make up the major part (about 85 per- cent) of the spawning population, age group I about 9 percent, and age group III about 4 percent. The short life and early maturity make the largescale menhaden a rapidly renewable resource. TULANE STUDIES IN ZOOLOGY VOLUME 1, 1953-54 Number Price 1 On a new genus and species of mysid from Louisiana (Crustacea, Malacostraca), by Albert H. Banner, pp. 1-8 (June 1, 1953) . .*0.25 2 A contribution on the life history of the lizard Scincella latcrale (Say), by llichard M. Johnson, pp. 9-27 (July 3, 1953) 75 3 An outline for the study of a reptile life history, by B'red R. Cagle, pp. 29-52 (July 28, 1953) 75 4 A population of Holbrook's salamander, Eurycea longicauda yuttolineata (llol- brook), by Robert E. Gordon, pp. 53-60 (August 15, 1953) 25 5 A redescription of the crawfish Procam- barus hinei (Ortniann) (Decapoda, Astaci- dae), by George Henry Penn, pp. 61-68 (September 1. 1953) 25 6 A new burrowing crawfish of the genus Procambarus from Louisiana and Missis- sippi (l>ecapoda, Astacidae), by George Henry Fenn, pp. 69-76 (September 15, 1053) 25 7 The life history of the crawfish Orconectes (t'axonella) clypeatus (Hay) (Decapoda, Astacidae), by Elsie Wayne Smith, pp. 77- 96 (October 23, 1953) 50 8 Ostrincola gracilis C. B. Wilson, a parasite of marine pelecypods in Louisiana (Cope- poda, Cyclopoida), by Arthur G. Humes, pp. 97-107 (December 21, 1953) 25 9 Hybrid inviabillty between U'ann pipiens from Wisconsin and Mexico, by B. Peter Volpe. pp. 109-123 (February 8, 1954) 35 10 The butterflies and skippers of Louisiana, by Bdward Xelson Lambremont, pp. 125- 164 (April 30. 1954) 60 11 Two new species of the genus Graptemys, by Fred H. Cagle. pp. 165-186 (August 26, 1954) 75 12 The taxonomlc status of the mid-Gulf Coast Amphiuma. by Imogene R. Hill, pp. 189-215 (August 26, 1954^ 35 Complete volume. Including title page and table of contents. ( unbound i $4.25 VOLUME 2, 1954-55 1 A new Eulimnadta from the rice fields of Arkansas with a key to the American species of the genus (Conchostraca, Lim- nadlldae), by N. T. Mattox, pp. 1-10 (Sep- tember 14, 1954) $0.25 2 Studies in the ecology of the narrow- mouthed toad, Microhyla carolhiensis caro- linensis, by Paul K. Anderson, pp. 13-46 ( November 8, 1954 ) 50 3 A new species of Diaptomus from Louisi- ana and Texas with notes on the subgenus Leptodiaptomus (Copepoda, Calannida), by Mildred Stratton Wilson, pp. 47-60 (No- vember 29, 1954) 25 4 Three new spectes and new records of southern mllllpeds, by Nell B. Causey, pp. 61-68 (December 28. 19.54) 25 5 Notropis baileyi, a new cyprlnid fish from I'ascagoula and Mobile Bay drainages of Mississippi and Alnbama. by Royal D. Surtkua and Edward C. Raney, pp. 69-86 January 12. 19.=i5t 30 6 A reconsideration of the racer Coluber constrictor. In eastern T'nltpd Statps. by Walter Auffenberg, pp. S7-155 (February 25, 1955) 1.00 VOLUME 2. 1954-55-Continued Number Price 7 Notropis hypsilepis, a new cyprlnid fish from the .Vpalachicola River system of Georgia dnd Alabama, by Uoyal D. Suttkus and Edward C. Raney, pp. 157-170 (Feb- ruary 25. 1955) 30 8 The fishes of two Gulf Coastal marsh areas of Floiida, bv John D. Kilby, pp. 171-247 (May 4, 1955) 1.00 Complete volume. Including title page, table of contents and index (unbound) . . . .$3.75 VOLUME 3, 1955-56 1 Notropis asperifrona, a new cyprlnid fish from the Mobile Bay drainage of Alabama and Georgia, with studies of related spe- cies, by Royal D. Suttkus and Edward C. Raney, pp. 1-33 (July 8, 1955) $0.50 2 A new Louisiana copepod related to Diap- tomus (Aylaodiaptoinua) claripes Schacht (Copepoda, Calanoida i, by Mildred Strat- ton Wilson, pp. 35-47 (August 1, 1955) ... .30 3 A new species of SIternotherus with a dis- cussion of the Sternotherus ca/rinatu8 com- plex (Chelonia, Kinosternidae), by Don- ald W Tinkle and Robert G. Webb, pp. 51-67 (August 30. 1955) 50 4 A new Vambarus of the Diogenes section from North Louisiana (Decapoda, Astaci- dae), by George Henry Penn, pp. 71-81 ( September 30, 1955 ) 25 5 Notropis curyzonus, a new cyprlnid fish from the Chattahoochee River system of (Jeorgla and Alabama, by Royal D. Suttkus, pp. 83-100 (December 28. 1955) 50 6 Factors Influencing the rate of oxygen con- sumption of the dwarf crawfish, Camba- relluM shufeldtii (Decapoda Astacidae), by Milton Flngerman, pp. 101-116 (December 28. 19.55 » 85 7 Identification and geographical variation of the cyprlnodont fishes Fundulus oliva- ceus (Storer) and Fundulus notatua (Rafl- nesqnet. by Jerram L, Brown, pp. 117-134, (February 3, 1956) 50 8 The physiology of the melanophores of the Isopod Idothcn exotica, by Milton Flnger- man. pp. 137 148 (April 12. 1956) 30 9 Osmotic behavior and bleeding of the oyster Crassostrea virginica, by Milton Fln- german and l^urence D. Fairbanks, pp. 149-168 (April 12. 1956) 50 10 Anatomy of the eyestalk of the white shrimp, Peniieus setiferua (Linn. 1758), by Joseph H. Young, pp. 169-190 (June 22, 1956) 50 Complete volume. Including title page, ta- ble of contents and Index (unbound) $4.00 VOLUME 4, 1956 1 A Study of the distribution and taxonomy of the percid fish Percina nigrofaaciata (Agasslz), by Ronald W. Crawford, pp. 1- 5.=i ( 4iiiruat 1. 1956 > $0.76 2 Experimental Pi hybrids between Bufo vallicrps and Rufo fowleri, by E. Peter Volpe, pp. 59-75 (September 30, 1956) 40 3 An outline for the study of an amphibian life historv. bv Fred R. Cagle, pp. 77-110 (October 31. 1956) 40 4 Notes on habitats, systematic characters and life histories of Texas salt water Cyp- rinndontes. bv Don G. Simpson and Gordon Gunter, pp. 113-134 (December 31, 1956) .35 TULANE STUDIES IN ZOOLOGY VOLUME 4, 1956-Continued Number Price 5 Domlnance-subordinance relationships in tlie crawfish Cambarellus ahufeldtii, by Mildred Eileen Lowe. pp. 137-170 (Decem- ber 31. 19.56) 45 6 Propogation of the white shrimp, Penaeun aetiferua (Linn.) In captivity, by Malcolm C. Johnson and J. R. Fielding, pp. 173-100 (December 31. 1056) 30 Complete volume, including title page, ta- ble of contents and Index (unbound) $2.50 VOLUME 5, 1957 1 Oambuxia heterocliir, a new poeciliid fish from Texas, with an account of Its hybrid- ization with O. affinia. by Clark Hubbs, pp. 1-16 (March 18. 1957) $0.30 2 New calanoid copepods of Pontella Dana and Lahidocera Lubbock with notes on the distribution of the genera in the Gulf of Mexico, by Abraham Fleminger, pp. 17-34 (March 18. 1957) 30 3 Three new crayfishes from Alabama and Mississippi (Decapoda: Astacidae), by Hwrton H. Hobhs, Jr. and Margaret Wal- ton, pp. 37 52 (March 18. 1957) 30 4 Heat death and associated weight loss of the oyster Craaaostrea I'iruinica, by Milton Fingerman and Laurpnce D. Fairbanks, pp. 53-62 (April 1. 1957) 30 6 The Odonata of Louisiana, by George II. Blck. pp. 69-135 (May 15. 1957) 1.00 6 Endocrine control of the red and white chromatophores of the dwarf crawfish. Cambarellua ahufeldti, by Milton Finger- man, pp. 137-148 (June 7. 1957) 30 7 Hormones controlling the chromatophores of the dwarf crawfish, Cambarellua ahu- feldti: their secretion, stability, and sepa- ration by filter pappr electropbore.'^is, by Milton Fingerman and Mildred E. Lowe, pp. 149-171 (June 7, 1957) 40 8 Cyprlnld fishes of the subgenus Vyprinella of Notropis. III. Variation and subspecies of Notropis venustus (Girard). by Robert H. Glbbs. Jr. pp. 173-203 (August 7. 1957) .50 9 The earlv development of Rami capita aevo- aa. by E." Peter Volpe. pp. 205-225 (Septem- ber 12. 1957) 35 11 The skeleton shrimps (Crustacea: Caprel- lidae) of the Gulf of Mexico, by Joan E. Steinberg and Ellsworth C. Dougherty, pp. 265-288 (December 30. 1957) 40 10 Variation and subspecies of the crawfish Orconectea palmeri (Faxon) ( Decapoda, Astacidae), by George Henry Penn. pp. 229-262 (September 12. 1957) 60 12 The systematic status of the suckers of the genus Moxoatoma from Texas, New Mexico, and Mexico, by C. Richard Robins and Edward C. Raney, pp. 289-318 (Decem- ber 30. 1957) 45 Complete volume, including title page, ta- ble of contents and Index (unbound) ....$5.00 VOLUME 6, 1958 1 The systematics and ecology of the Sterno- thaerua carinatua complex (Testudinata, Chelydrldao), by Donald W. Tinkle, pp. 1-56 (March 31. 1058) $1.25 2 The butterflies of Mississippi, by Bryant Mather and Katharine Mather, pp. 61-109 (June 6. 1958) 1.00 3 Aquatic and somiaquatic Ilemlptera of Mis- sissippi, by Clifton A. Wilson, pp. 113-170 (September 5, 1958) 1.00 VOLUME 6, 1958-Continued Number Price 4 The copepod genus Halicyrlopa in North America, with description of a new species from Lake I'ontcliartrain, Louisiana, and the Texas coast, by Mlldrpd Stratton Wil- son, pp. 176-1R9 (Oecemhpr 31, 1958). OntojiPny of the first and second pleopods of the male crnwfish Orconectps clypeatus (llay) (Decapoda. Astacidae), by Joe B. Black, pp. 100-2113 (December 31. 1958) ... .60 Complete volume, includlnir title page, table of contents and index (unbound) $3.50 VOLUME 7, 1959 1 An illustrated key to the crawfishes of Louisiana with a summary of their distri- bution within the State (Decapoda, Asta- cidae). by George Henry Penn, pp. 3-20 (April 23. 1959). Comparison of the chromatophorotroplns of two crayfishes with special rpference to electrophoretic behavior, by Milton Finger- man. pp. 21-30 (April 23. 1959) $0.60 2 A review of the seabassea of the genus Centropriatea (Serranidae). by Rudolph J. Miller, pp. 33-68 (July 9, 1959) 75 3 Digenetic trematodes of marine fishes from the Gulf of Panama and Bimini. British West Indies, by Franklin Sogandares-Ber- nal. pp. 69 117 (August 24. 1959) 1.00 4 Parasites of the commercial shrimps. Pen- aeus aztecun Ives, P. duorarum Burkenroad. and P. xrtiferua (Linnaeus), by Dwayne Nathaniel Kruse. pp. 123-144 (October 19, ior.9). The larva of the oak toad. Bufo quercicua Holhrook. bv E. Peter Volpe and James L. Dobie. pp. 145-152 (October 19, 1959) 60 Coniplpfe volume, including title page, table of contents and inilex (unbouud) $2.65 VOLUME 8, 1960 1 Studies on the backswimmers of Costa Rica (Ileraiptera; .N'otoncctidae). by John L. De Abate, pp. 1-28 (April 29. 1960) $0.60 2 Three Ascocotyle complex trematodes (Ilet- erophyidae) encysted in fishes from Louisi- ana, ■including the description of a new genus, by Franklin Sogandares-P.ernal and John F. 'Bridgman. pp. 31-39 (October 28, 19G0) Age and growth of the spot, Leioatomua .rnnthiirufi Lacfip^de. by Bangalore I. Sun- dararaj, pp. 41-62 (October 28, 1960) 65 3 The breeding habits of the mole salaman- der, Ambystoma talpoideum (Holbrook), in southeastern Louisiana, by C. Robert Shoop, pp. 05-82 (December 2, 1960) Salinity relations of some fishes In the Aransas River. Texas, by William C. Ren- fro, pp. 83-91 (December 2, 1960) oO 4 Ecology of the rice rat, Oryzomys paluatris (Harlan), on Breton Island, Gulf of Mexico, with a critique of the social stress theory, by Norman C. Negus, Edwin Gould, and Robert K. Chipman. pp. 93-123 (May 10, 1961) 6" 5 A quantitative study of the movement of J'aniiiicciuni cauddtum and P. multimicro- vitrlcatinn, by 1). F. Scars, and Lila Elve- back. pp. 127-139 (May 31, 1901) Nine digenelic trematodes from the Altantlc Coast of I'annnia, bv Franklin Sogandares- liernal and Lucy McAlister Sogandares, pp. 141-153 (May 31, 19U1) GO Orders should be addressed to Meade Natural History Library, c/o I^epartment of Zoology, Tulane University. New Orleans, 18, La.. USA Please make remittance payable to "Tulane University' *-VVi{ TULANE STUDIES IN ZOOLOGY VOLUME 8 INDEX TO AUTHORS AND SCIENTIFIC NAMES (New species and genera in boldface) Ahudefduf saxatilis, 145 Acanthostomidae, 37 Acanthostomum, 37 Acris gryllus, 66 Agelaius phoenicens, 98 Amhystoma jeffersoniaiium, 77, 79 macuIatiDU, 79-80 opaciim, 79-81 talpoideum, 65-81 tigrinum, 79-80 tigrinnm nehidosnm, 80 Ambystomatidae, 65 Anacharis, sp., 66 Anas rubfipes, 98 Anchoa mitchilli, 86, 90 Ancistrodon piscivoriis, 98 Anisotremus virginicus, 143 Ayiolis carolinensis, 98 Ascocotyle, 31-38 angeloi, 36 Ze2>£^/ii, 31-32,37-38 megaloccphala, 31 Avzce»}u"c( nitida, 96, 98 Baccharis huUinifoUa, 96-98 Bairdiella chi-ijsnra, 86, 89-90 BalauHS, sp., 157 Batis viaritima, 98 Blarina brevicanda, 66, 109 Borrichia frutescens, 98 Brevoortia patronus, 86, 90, 177-182 BridgTiian, John P., article, 31-39 Bucephalidae, 141 Bucephcdoides, 142-143 arcitatus, 141 lo)igoviferiis, 141 Bucephcdopsis, 142 arcuatHs, 141-143 longovifei'us, 141-143 Bucephalus, 141 antigone, 5, 23 crassipes, 4, 19, 22, 24-26 gracilis, 5, 23 irfa, 5, 23 livuiocastoris, 13, 15, 18, 24 margaritacea, 13-14, 18 jmllens, 4, 19, 22, 24, 26 pallipes, 4, 21, 25-27 Caitnanicola, 37 Caiman sclerops, 37 Cakile edentata, 97 Cambarelbis sliufeldti, 157-175 Cassidix mexicaiius, 98 Catoptropho)-ns semipal))iatiis, 98 Celtis mississippiensis, 66 Centrocestiis, 38 armatus, 37 formosanns, 37 Cercaria liaimcana, 141-142 Chaenobnjttus gulosiis, 86, 89-90 C/iaefocZo/i capistratus, 147, 149 ocellatus, 147, 149 Chaetodontidae, 147, 149 Chipman, Robert K., article, 93-123 Chordeiles minor, 98 Cichlosoma cijanogiittatnm, 86, 89-90 Ciliata, 77 Circus cijaucHS, 98 Citharichthys sordidus, 52 Cladophora, sp., 84 Clethrionomys gapperi, 109 Coccyzns americanus, 98 Crassostrea virgiiiica, 157 Croton piinctatns, 98 Cryptogonimidae, 149 Cryptotis parva, 66, 100 Culex, sp., 15 Cyiioscioii regalis, 43 Cyperus panicidatns, 98 Cyprinodon variegatus, 32, 37-38, 86-88 Dawbentonia drummondii, 96-97 de Abate, John L., article, 1-28 Didelphis marsupialis, (SQ Dicmictylns viridescens, 66 Digenea, 141, 147, 152 Dormitator maculatus, 86, 90 cepedianum, 86, 90 petenense, 86, 90 Elassoma zonatum,, 66 Eleocharis caribaea, 98 Elodea, 172 Elveback, Lila, article, 127-139 Endogonaceae, 109 Endogone, sp., 109, 120 Ereclitites hieracifolia, 98 Eucinostomus argenteus, 86, 89-90 Eurycea bislineata, 79 Fimbristylis castanea, 95, 97-98, 120 Fif7(ff»/«S gravdis, 32, 37-38, 86-88, 90 heteroclitiis, 32 jenkinsi, 32-33, 37-38 tnajalis, 32 paUidiis, 32 similis, 32, 37 Gambiisia af finis, 66, 86, 88, 90 Gasterostonmm arcuatum, 141 Geothlypis trichas, 98 Gobioso))ia bosci, 86, 90 Gould, Edwin, article, 93-123 Halichoeres bivitattns, 149 Hamacreadium mutabile, 143 Haplosplanchnidae, 145 Haplosplanchnus acntns, 145 pomacentri, 147 pachysomus, 147 purii, 147 Heliotropiu)>i curassavicum , 98 Hemiptera, 1-28 Hemiuridae, 150 Heterophyidae, 31-39 INDEX TO AUTHORS AND SCIENTIFIC NAMES— Continued Hurley trematoides chaetodoni, 149 Hydra )iassa tricolor riificollis, 33, 98 Hydrocotyl nmbrellata, 98 Hyla, sp., 15 Hymenolepis nana, 37 Ictalurus melas, 66 fiircatus, 86-87, 90 Icterus spurius, 98 I])ot)toca a)ig list if alia, 98 Jassidae, 15 Jnncus validus, 98 Kinosternon snhruhrnm, 66 Labridae, 149 Lacerdaia, 38 Lampropeltis getuliis holbrooki, 98 Larits ai-gcutatns, 33 Leiostonius xayithiirns, 41-61 Lepidium vi)-gi}iicn))i, 98 Lepidochelys olivacea, 98 Lepisosteus spatula, 85-86, 90 Lepocreadiidae, 147 Lcponiis macrocliirus, 86, 89-90 megalotis, 86, 89-90 Leucophoyx tliula, 98 Liquidamber styraciflua, 66 Lowe, Mildred Eileen, article 157-176 Lucauia parva, 32, 37-38, 86-88, 90 Lutjmius analis, 143 apodus, 143 grisens, 143 yoc2(, 143 synagris, 143 ,149 viridis, 143 Lutra canadensis, 98 Lygosoma laterale, 98 Malaclemys terrapin, 98 Mastig'ophora, 77 Meliponidae, 15 Menidia beryllina, 86, 88-90 Mephitis mephitis, GQ Micropogon nndiilatus, 59 Microptems salmoides, 66, 86, 89-90 Microtus, 113, 118-119 gucuthcri, 112 vioitaiins, 118-119 ochroguster, 119 penusylvaivicus, 101, 113, 118 Mollienisia latipinna, 31-33, 37-38, 86, 88 Monorchiidae, 149 Mugil cephalus, 37, 86, 88-90 curema, 37, 86, 89-90 Multitestis chaetodoni, 147 M»s, sp., 113 Miisca, sp., 15 Mycteroperca xcnarcha, 143 Myocuster copyus, 98 Myriea cerifera, 96, 98 Matrix sipedon clarki, 98 Negus, Norman C, article, 93-123 Neoapocreadium colli, 149 Nofonecfa borealis, 13-14, 17 ceres ceres, 3-10, 12-15, 22 ceres rogersi, 6-8 ce>Ts stirtoni, 6 confnsa, 4, 18 indica, 4, 16, 22 insulata, 13-14 irrorata, 13-14, 17 Dic.vicaiia, 5-6, 11 ochrothoe, 4, 18 raleighi, 13-14,20 nndulata, 13-15, 20 Notonectidae, 1-28 Notropis lut)-e)isis, 86, 90 Nycticoiax nycticorax, 33 Ocyurus chrysurus, 143, 149 Ondatra zibethicus, 98 Opecoelidae, 143 Opuntia, 96-97 Jiuniifasa, 98 Orco??ecfes clypeatus, 158 rusticus, 157 virilis, 157 Oi-yctolagus, sp., 119 palustris, 93-123 xauthaeolus, 95 Ostrea edulis, 157 ParameciMm caudatum, 127-138 mnltimicronucleatnm, 127-138 Parascocotyle diminnta, 31-34,37-38 lagen iform is, 31-34 Patella vulgata, 157 Pelecanus occidentalis, 98 Pero7Ji)/«c»s gossyj)i)ius, 66 leucopus, 109 maniculatus, 109 polionotns, 106 Phagicola, 33, 36-37 lo)iga, 37 )ia)ta, 33 Phalacrocorax auritus floridanus, 33 Phormidum, sp., 84 Pinus taeda, 66 Pofl, 118-119 Pomacentridae, 147 Pomacentriis lencostictus, 147 pla)iifro)>s, 147 Procd inlxnus blandiiigi, 158 clarkii, 151, 175 Procyon lotor, 33, 98 Pseudarris triseriata, 66 Pseudascocotyle, gen. nov., 33-36, 38 mollienisicola, sp. nov., 33-36 Pygidiopsis, 38 Pygidiojisoides, 37-38 Quercus Virginia na, 66 Rallus longirostris, 98 INDEX TO AUTHORS AND SCIENTIFIC NAMES— Continued clamitans, 66 pipiens, 66, 77 Raftus, sp., 113 Reith)'odonto))iys, 100 Renfro, William C, article, 83-91 Reporhamphits Dielanocheir, 42 Rhy)ico^j)ora, sp., 158 Rivuhis, sp., 15 Ruhiis trivialis, 98 Rumex per sicario ides, 98 Rynchops nigra, 98 Sabatia stellaris, 98 Salico)-)iia, sp., 98 Sarcodina, 77 Sarda sarda, 141 Scirpus naHas, 158 Scomberomorus, regalis, 141 Scomber scoinbrns, 141 Sciurits caroUnensis, 66 Sears, D. F., article, 127-139 Shoop, C. Robert, article, 65-82 Sigmodou, 100, 103, 115, 117-119 hispidus, 118 Siphodera vittaledivardsi, 149 Siren intermedia, 66 Smilax, sp., 66, 98 Sogandares, Lucy McAlister, article, 141- 153 Sogandares-Bernal, Franklin, articles, 31- 39, 141-153 Sorex cinereus, 109 fumeus, 109 Spartina patens, 98 Sphyraena barracuda, 141, 143 Stephanosto))U()u baccatnm, 37 Sundararaj, Bangalore, articles, 41-62, 177-182 Suttkus, Royal D., article, 177-182 Syliilagns aquaticiis, 66, 98 Synaptomys cooperi, 109 Sygiiathus scovelli, 86-87, 90 Tabanidae, 15 Theletrum magnasaccum, sp. nov., 150-152 Trinectes maadatns, 86, 90 Tropicorbis, sp., 15 Tyto alba, 98 Uniola paniculata, 98 Yucca, sp., 96-97 gloriosa, 98 I