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Fishery Bulletin 100(4) 



resolution radiography (in Cape Town). A pin was inserted 

 perpendicular to the upper origin of the caudal fin to count 

 the precaudal vertebrae. Distinct shortening of the centra 

 was used to distinguish between monospondylic and dip- 

 lospondylic vertebrae. 



Dentition and mucous denticle examination 



We used the term "embryonic teeth" for teeth in an embryo, 

 which do not resemble teeth in the adult (Gilmore, 1993). 

 We used "row" for teeth at the same developmental stage 

 in the mesial-distal direction and "file" for teeth at dif- 

 ferent developmental stages in the labiolingual direc- 

 tion derived from a single locus (tooth germ) (Zangerl, 

 1981). We followed Applegate (1965) for the terminology 

 anterior, intermediate, lateral, and posterior teeth and 

 for the definition of the dental formula. This terminology 

 and definition apply to fully formed dentition in postnatal 

 sharks but they appeared to be applicable to the embryo 

 under investigation. If a tooth was missing in the first row, 

 the one behind it was counted. We used the term "mucous 

 denticles" for dermal denticles in the oral cavity (Yano et 

 al., 1997). We examined the mucous denticles with a Leitz 

 DMRB microscope at 25x and 45x magnification. 



The jaws could not be removed; therefore a nondestruc- 

 tive examination was carried out with close attention to 

 the positions of teeth in the functional and replacement 

 rows in the upper jaw. The functional tooth and the first 

 replacement tooth in the fifth file (counted from the sym- 

 physis) of the upper left jaw were extracted and examined 

 through a Leitz DMRB microscope at 25x and 45x magni- 

 fication. The examination of replacement teeth required 

 lifting the tissue that covered the developing teeth. The 

 lower jaw was not examined as closely because only one 

 tooth was visible to the naked eye. 



We measured enameloid height (E2), if possible, for all 

 teeth in the upper jaw (Mollet et al., 1996). We estimated 

 the total vertical height (H) of the largest tooth, from a 25x 

 photograph showing the outline of the root, for comparison 

 with the likely total heights reported by Sanzo ( 1912). We 

 calculated the enameloid height of each tooth in relation 

 to the third tooth. For comparison, we estimated tooth 

 sizes in relation to the third tooth of postnatal shortfin 

 makos from photogi'aphs or drawings (Bigelow and Schro- 

 eder, 1948; Bass et al., 1975; Compagno, 1984). 



Dissection 



The Sanzo and the Uchida embryos were dissected conser- 

 vatively in order to examine the internal structure of the 

 head, jaws, and pectoral fins. The chondroneurocranium 

 was exposed dorsally and on the left side by dissecting 

 away flaps of skin, muscle, and connective tissue. We 

 examined the structure of the ethmoid region, epiphysial 

 area, orbital process, and otic capsule. Dissection of the 

 left lateral surface of the embryos head exposed the pala- 

 toquadrate and allowed observation of the proportions of 

 the palatine process. Dorsal dissection of the pectoral fin 

 allowed examination of the basal metapterygium's skel- 

 etal structure. No white shark embryo of suitable size was 



available for dissection and direct comparison. The white 

 shark embryo (TL=55 cm) described by Parker ( 1887) was 

 a misidentified Carcharhinus (Francis, 1996). 



Results 



General condition and morphometries 



After more than 90 years of storage in a glass container 

 in 75% ethanol, the 36.1-cm male Sanzo embryo (MZUF 

 5911) was curled up, and fins and other body parts were 

 permanently bent (Fig. lA). The jaws appeared protruded, 

 possibly because of the strong retraction and shrinkage of 

 the snout. The large yolk stomach was hardened. It was 

 13.4 cm long, 8.6 cm wide, and 6.9 cm high and had an 

 estimated volume of 416 cnr^. The embryo weighed 0.548 

 kg (condition factor, CF=11.7 kg/m^) compared with 0.800 

 kg (CF=17.1 kg/m^) reported by Sanzo (1912). The 31.5% 

 mass loss was likely due to dehydration and dissolving and 

 leaching of lipids from the yolk and liver into the ethanol. 

 Despite this, the embryo did not appear to have shrunk in 

 length because it still measured 36.0 cm TOT, 30.0 cm fork 

 length (FOR), 27.4 cm precaudal length (PRO. 



After 16 years in formalin, the female Uchida embryo 

 (SAM-35742) looked shriveled (Fig. IB). The embryo mea- 

 sured TOT = 35.8 cm, FOR = 28.8 cm, PRC = 26.6 cm, mass = 

 1.227 kg on 6 June 2001. The condition factor of 26.7 kg/ 

 m-* of this embryo was similar to that calculated from the 

 reported mean length and mass of all the embryos of the 

 litter by Uchida et al. (1987) (CF=23.8 kg/m*). TOT was 

 almost the same as that of the Sanzo embryo, but this em- 

 bryo weighed almost twice as much as the Sanzo embryo. 

 Accordingly, the yolk stomach was considerably larger and 

 was 18.5 cm long, 9.6 cm wide, and 11.5 cm high and had 

 an estimated volume of 1069 cm '. 



Sanzo (1912) used the upturned snout, as one of four 

 characters to distinguish his embryo from a shortfin mako, 

 but this feature is probably an artifact of preservation (see 

 "Skeletal anatomy" below). The three quantifiable mor- 

 phometric characters used by Sanzo (1912) were also not 

 suitable to distinguish between small white and shortfin 

 mako sharks (Fig. 2). White sharks generally have a wider 

 mouth, in relation to its length, than shortfin makos, but 

 there is significant overlap (Fig. 2A). Furthermore, the ra- 

 tio of mouth width to length (MOW/MOD is allometric in 

 small shortfin makos; mouth width becomes progressively 

 larger than mouth length in smaller embryos. White and 

 shortfin mako sharks both have slightly oval to round eyes 

 and an eye length-to-height ratio between 0.9 and 1.3 (Fig. 

 2B). The origin of the anal fin is behind the origin of the 

 second dorsal fin (PAL-PD2 > 0) in both white and short- 

 fin mako sharks (Fig. 2C). 



Two promising morphometries not considered by Sanzo 

 (1912) also proved unsuitable for identification. The first 

 dorsal fin origin (PDl) of the Sanzo embryo was 2.3 cm 

 (6.4% TOT) behind the pectoral fin rear tip (PRT), which 

 suggested it might be a shortfin mako following Compagno 

 (1984). However, the origin of the dorsal fin in both white 

 and shortfin mako sharks varies from slightly-in-front-of 



