5 8 Memoir Sears Foundation for Marine Research 



has quoted somewhat higher figures than those given in Table v for the shields: 10—14 

 in the dorsal row (excluding the nuchale) and 25—36 in the lateral row (2). Antoniu, 

 for A. sturio from the Black Sea, mentioned the presence of pairs of postdorsal shields 

 and of a frontal sinus in the cartilaginous skull ; both of these characters are found 

 in A. oxyrhynchus (^: 109— 116). 



Of two specimens obtained by Cope nearly a century ago in Adige (Verona), Italy, 

 and labeled A. sturio, one is probably A. guldenstddti (ANSP 646) and the other is 

 definitely an A. sturio (ANSP 645), 15 inches long (380 mm) FL. The latter has a 

 fontanelle, 10 shields (including nuchale) in the dorsal row, and 30 shields (including 

 supracleithrum) in the lateral rows. On the first branchial arch we counted 20 gill 

 rakers. The body proportions are also very similar to those of A. oxyrhynchus of cor- 

 responding size, and its color, or what remains of it, corresponds very closely to that 

 of American specimens. 



In a drawing of A. sturio by d'Ancona, the coloration is also very similar to 

 that of the western Atlantic Sturgeon (2: fig. i); on the other hand, the mouth of 

 d'Ancona's A. sturio is larger than that of A. oxyrhynchus (2 : fig. 2), the shape of its 

 lower lip is very different, and there are other differences as well. According to Berg, 

 the adult of A. sturio has several (up to 10—12) dense, oblique series of rhombic plates 

 (dermal ossifications) between the dorsal and lateral rows of shields (jJ: 97); in western 

 Atlantic specimens these ossifications are much less developed and are rather irregular 

 in shape. Moreover, Classen {20: 88—102) has mentioned several ripe females of 

 sturio from the Gulf of Cadiz, Spain, d^ inches TL (145 cm FL) and weighing as 

 little as 62 pounds (28 kg); oxyrhynchus apparently attains sexual maturity at a larger 

 size than sturio, the males of oxyrhynchus being approximately six feet TL and 70 

 pounds in weight, the females not less than 150 pounds (p. 51). 



In Europe, probably because of a general scarcity of A. sturio {2^: 5—13), little 

 work has been done to elucidate the problem of local races. Nevertheless, there are 

 observations by Marti that A. sturio from the Black Sea are similar to those from the 

 Mediterranean region but differ from those of the Baltic (5J: 435—442, Russ.); 

 the Black Sea specimens have on the average higher numbers of dorsal and lateral 

 scutes and dorsal rays. Magnin, by studying cross sections of the pectoral ray, found 

 that the rate of growth of the European Sturgeon varies according to geographical 

 region {^g\ 152-159). The growth observed was fastest in Italy (Tiber and Po rivers), 

 intermediate In Spain (Guadalquivir River), and slowest in France (Gironde River). 



In conclusion, until an adequate comparison of anatomical and meristic characters 

 of these two species is made, it is preferable to retain separate specific rank for A. 

 sturio and oxyrhynchus. 



