1.31a Internal morphology 3 



The nostrils are separated by a cup-shaped space 

 but are enclosed in a common cavity (Poey, 1861). 

 The olfactory rosette is radially shaped and has 44-50 

 nasal lamina, the distribution of blood vessels on 

 which cannot be seen with the naked eye (Nakamura 

 et al., 1968). The structure of the skull and bill are 

 well described by Poey (1861) and Nakamura et al. 

 (1968). The following description of the skull and of 

 vertebral characteristics are from the latter authors. 



The cranium is hard, elongated, and on the whole, long and 

 thin. The post-occular portion of the head is short. The anterior, 

 ventral side of the vomer and the parasphenoid is rather thin. 

 The temporal crest and the pterotic crest run almost parallel to 

 each other. There is a small and fairly well developed projection 

 on the upper back side of the frontal bone. 



The haemal spines and the neural spines of the vertebrae form 

 an elongated parallelogram. The lateral apophysis is poorly 

 developed. There are 24 vertebrae (12 + 12 = 24). 



The vertebral characteristics of white marlin and 

 other istiophorids were discussed and compared in 

 detail by Ueyanagi and Watanabe (1965), and Monod 

 (1968, Fig. 784) described the osteological structure of 

 the caudal region. Morrow (1957) studied and com- 

 pared the morphology of the pectoral girdle in the 

 genus Makaira, including T. albidus. 



The internal organs of white marlin were described 

 briefly by Poey (1860) and Nakamura et al. (1968), 

 and Krumholz (1958) provided information on 

 relative weights of some of the viscera. The following 

 description is abstracted from the more comprehen- 

 sive work of LaMonte (1958b), from which we show 

 the ventro-lateral aspect of the viscera (Fig. 3). The 

 kidneys lie at the top of the body cavity against the 

 vertebrae. The peritoneum separates them from the 

 long, physoclystic air bladder, which consists of a dou- 

 ble row of bubblelike chambers closed in a common 



3 This section heading has been introduced by the authors since 

 the outline provides no place for this material. 



outer membrane. The stomach is at the anterior end 

 of the body cavity, and below it, anteriorly, are the 

 caecal mass, capped by the liver, and the heart. The 

 spleen is below the stomach on the left side, behind 

 the caecal mass. Adjacent to it is the intestine, which 

 makes one coil upon itself and runs along the body 

 wall to the vent which lies in a ventral groove with the 

 urinogenital opening. The gonads lie on either side of 

 the stomach. Krumholz (1958) presented the relative 

 weights of different organs of 42 white marlin caught 

 off the Bahamas in percentage of the weight of the 

 fish, and discussed their variations with the size and 

 sex of the fish. 



No analyses of geographic variations in 

 morphological characters were found in the literature, 

 and consequently no subpopulations have been de- 

 fined on this basis. 



Morphological changes with growth have not been 

 well defined, since nearly all of the available 

 morphological data is for adults, and no thorough 

 compilation and analysis of this have been published. 

 Robins and de Sylva (1960), pointed out that the 

 development of the bill in Tetrapturus albidus and 

 other "Tetrapturinae" was negatively allometric. The 

 bill length (30) of the 125 mm (body length) postlarva 

 described by de Sylva (1963), however, falls in the 

 range for adult material (25-35). The first dorsal fin of 

 this specimen is high medially (25th ray 30) and 

 saillike. The pectoral fin is much shorter than in 

 adults (10.7 vs. 19-27) and the pelvic much longer 

 (29.6 vs. 14-22). The body is more slender and com- 

 pressed (greatest depth 11 vs. 12-18, greatest width 

 5.8 vs. 5.2-9.4, usually 7.5-8.5), with the greatest 

 width near the orgin of the pectorals rather than near 

 the origin of the first anal fin as in adults. 



Data (unpublished) for two specimens of in- 

 termediate size (904- and 964-mm body length) ex- 

 amined by C. R. Robins and Mather are available. In 

 general, these individuals had attained adult propor- 

 tions except that the central part of the first dorsal fin 

 remained higher (14.7 vs. 3.1-4.7), the pectorals 



Figure 3. — Diagram of Makaira albida, showing ventral-lateral aspect, with 

 caecal mass reflected to left. Approximately natural size. Dissection by 

 Francesca R. LaMonte. Drawing by Janet Roemhild. (From LaMonte, 

 1958b, Fig. 13 and caption.) 



61 



