987 



Leilath of the bndv cxpiesscil in millimelrcs 



Bwe of the mini tin in % of the length of the body 



„ „ „ ., „ „ , head 



„ ., ., „ ., „ „ dislauee lietnein the iinnl tin nnd the tip of the snout 



, „ postiibdcmiiniil length 



dorsal tin in =-. of the hnse of the iiunl tin 



length of the iiKixillaries ,, ., .. „ „ ., ., „ 



^, .. ., pectoral tins „ ,, ,. ., .. ,, v „ „ 



Irfnst de|.lll ..f Ihe tail ' 



121 

 14.7 

 (J2.8 



•21.8 



1)3.6 

 iKi.s 

 78.6 

 95.5 



ioy.4 



72.4 



57.8 



Clupea finta. 



348 



14.6 



64.5 

 21.1 



61.8 



92.7 



71.5 



90.8 

 99.1! 

 63.7 

 53.0 



393 

 16.0 

 72.0 

 24.0 



90,5 

 54.7 

 48.5 



Cluiiea a! OS a. 



147 

 16.0 

 64.8 

 22.6 

 70.3 

 80.0 

 71.1 

 93. s 

 103.5 

 60.0 

 53.3 



147 



18.1 



74.5 

 63. G 

 84.2 

 90.0 

 58.0 

 46.8 



321 

 17.1) 

 85.1 

 29.6 

 87:o 

 74. s 

 53.8 

 68.5 

 75.0 

 45.0 

 39.9 



358 



17.6 



74.1 

 26.9 

 80.0 

 79.3 

 63.5 

 74.6 

 84.1 

 52.4 

 42.S 



385 

 17.1 

 79.5 

 26.1 

 79.6 

 75.7 

 56.5 

 75.8 



80.3 

 50.0 



38.8 



Tlu' rule i.s clear: the young and the males have 

 the sliorte.^t anal tin, and the Allice Sliad is charac- 

 terized !)v tlie long base of its anal tin. Hut in this 

 character ihe young male of the Allice Shad — a Medi- 

 terranean s]iecimen 147 mm. long and sent here liy 

 Hedknbl.M) — ranks he.side the female Twaite Shtids, 

 and is so closely a|)j)roximated to them that the dif- 

 ferent'c is useless as a specific character. The chiiracter 

 is, however, not without importance, for we find on 

 comparison that in most of the relations the base 

 of the aiitil lin is much shorter in male Twiiite 

 Shads than in .\llice Shads less than half as long. 

 A develo})ment of form, determined by the female 

 characters, has evidently advanced i'rom finta" to alosa: 

 but this development has not yet attained such defini- 

 tene-ss that true species can be distinguished. The spe- 

 cific character first pointed out by Troschel, the dif- 

 ference in the number of the gill-rakers — greater in 

 alosa (tig. 249, h) than in finta (fig. 249, a) — is im- 

 paired bv the same indefiniteness. Steixdaciink.i; and 

 Moiii;.\r showed that their luimber increases with age, 

 \vhereu|ion Lill.jeb(ik(t remarked with justice that the 

 character ciin onh" be employed in comparisons between 

 specimens t)f about ei|nal size. The case appears to be 

 the same here as in the Gwyniads (see above), where 

 we also faileil to arri%e at more than variety distinc- 

 tions bv the iiid of the differences in the gill-rakers. 

 And even if we could prove that the character derived 

 from this source agrees in our European Shads with 

 other characters'', the North American Shad apjiareiitly 

 baffles our systematic calculations, for it is fur- 



nialied, according to .Tord.vn and Gilbert, with the 

 gill-rakers of the Allice Shad, but externally resembles, 

 according to Todd's figure in Brown-Goode (1. c), the 

 Twaite Shad. 



The form :ind texture of the scales (fig. 24"), /)) 

 we have described above. They are more firmly at- 

 tached to the skin in most cases than in the Herring. 

 The irregularity of their arrangement and the absence 

 of a lateral line render it difficult to comjnite their 

 number with certainty. The number of spiniferous 

 scales at the ventral margin is 37' in all the specimens 

 examined bv us, 2.') or 22 in front of the ventral fins 

 and 14 or lo behind them. Here too these scales are 

 covered to the greater part of their extent l)y the 

 nearest lateral scales. 



The coloration is essentially the same as that of 

 the Herring. The dark (blackish blue) spots charac- 

 teristic of the subgenus Alosa, set in a straight r)r an 

 interrupted (zigzag) row on the sides of the body, the 

 largest — sometimes as large as the eyes, but commonly 



smallei first, ;ire most usual in yoimg specimens. 



The\- formerh- ranked as a character of the Twaite 

 Shad, but are of very irregular occurrence even in this 

 variety. Our figure (I'late Xi>IIl, tig. 2) also , shows 

 that thev mav be ipiite numerous in the Allice Shad; 

 and Fatki relates rhat, on boiling adult Allice Shads 

 from the Rhine in order to prepare their skeletons, as 

 many as 1.5 spots a])peared on the sides of the body. 

 "On the sides of the head too," writes Kroyek of the 

 Twaite Shad, "a black spot may sometimes be seen 

 above the preoperculuin" ; and in one of our Twaite 



" Or perliaps from the North A 

 gression in development. 



' LlLUEBORG has adduced the different form of tlie tip of th 

 ■•■ 37 — 42, according to Valenciennes. 



an Clupea chr'/sochloris, with its still shorter anal tin. unless this form he an instance of retro- 



snoiit and the icreater nnmlii-r of tlie scales in alosa (see above). 



