Table 5. — .\feasurements of smallest, largest, and eight 

 randomly selected ovigerous females taken from Chilo- 

 mvcterus schoepfi at Morehead City, North Carolina (from 

 USXM 4774s) 1 



Specimen 

 number 



Average. 



Head 



Mm. 

 0.38 by 0.67 

 .30 by 0.78 

 .35 by 0.96 

 .37 by 0.91 

 .31 by 0.84 

 .34 by 0.88 

 .36 by 0.85 

 .37 by 0.91 

 .38 by 0.94 

 .40 by 0.89 



Neck 



Trunk 



Mm. 

 0.10 1, 

 .09 2. 

 .08,2, 

 .12 2. 

 .13 2. 

 .11 2. 

 .12 2. 

 .09 2. 

 .112. 

 .12 2. 



Mm. 



"Tail" 



Mm. 



76 by 1.65 0.18 by 0.24 



Egg 

 sac 



02 by 1.60 

 15 by 2.06 

 30 by 1 . 79 

 29 by 1.89; 



50 by 1.98' 

 39 by 1.95 



51 by 1.86: 

 49 by 2.42, 

 46 bv 1.95 



(2.79) 



17 by 0.23 



19 by 0.24 



16 by 0.25 



.16 by 0.261 



.16 by 0.24' 



.17 by 0.27 



.18 by 0.26 



.19by 0.27i 



.17by0.25| (4.61) 



Total 

 length 



0.36 by 0.86; 0.1112.39 by 1.92 0.17 by 0.25 . 



Mm. 

 2.24 

 2.47 

 2.63 

 2.79 

 2.80 

 2.90 

 2.97 

 2.98 

 3.09 

 3.16 



2.80 



' The egg sacs were found free in the vial. Since there is no way to identify 

 each sac with its female, only the shortest and the longest sacs were mea,sured. 



T.\BLE 6. — ^feasurements of smalle.'it, largest, and eight 

 randomly selected ovigerous females taken from Chilo- 

 mvcterus antennatus at Montego Bail, Jamaica (from USXM 

 4227S) 



Specimen 

 number 



Head 



Mm. 

 0.31 by 0.48 

 .32 by 0.54 

 .33 by 0.60 

 .35 by 0.56 

 .34 by 0.58 

 .35 by 0.59 

 .34 by 0.56 

 .33 by 0.66 

 .36 by 0.66 

 .34 by 0.68 



Average.. 0.34 by 0.59 



Neck 



Trunk 



•Tail" 



Egg 

 sac 



Total 

 length 



Mm. Mm. Mm. Mm. Mm. 



O.irO. 93 by 0.83 0.17 by 0.26 0.68 1.42 



.09 .96 by 0.78 .19 by 0.27 broken 1.46 



.091.15l)yl.l3 .18by0.25 1.02 1.S9 



.10 1.29 by 1.10 .16 by 0.27 1.77, 1.75 



.08 1.42 by 1.22 .18 by 0.26 broken! 1.78 



.11 1.35 by 1.29 .16 byO. 23 1.59 1.81 



.12 1.41byl.26 .15by0.24' 2.051 1.83 



.09 1.47 by 1.27i .18 by 0,26 2.14' 1.95 



.10 1.46 by 1.36 .18 by 0.25 broken' 2.00 



.11 1.67by 1.41J .17 by 0.26 broken! 2.14 



0.10!l.31by 1 



,17,0. 17 by 0.26 



1.77 



Mexico, and the Caribbean Sea. This variation 

 occurs only in the metamorphosed parts of the 

 body, and is in the size and the shape. A com- 

 parison of fig. 1 (a representative from the 

 Gulf of Mexico), fig. 24 (a representative 

 from the west coast of North Atlantic Ocean), 

 and fig. 26 (a representative from the Carib- 

 bean Sea) together with reference to tables 4, 

 5, and 6 shows this picture of geographical 

 variation. In the following discussion, for the 

 sake of convenience, the specimens from 

 Georgia, North Carolina, and Massachusetts 

 are termed as the Atlantic type ; the specimens 

 from Florida (west coast), Mississippi, and 

 Louisiana, the Gulf type; and the specimens 

 from Jamaica, the Caribbean type. 



The bilobed condition of the lateral wings of 

 the head is generally most pronounced in the 

 Caribbean type (figs. 26, 27), but the wings 

 are almo.st unlobed in the Gulf type (fig. 1). 

 The lateral wing of the Atlantic type (fig. 24) 



is only slightly bilobed; the posterior lobe is 

 larger than the anterior lobe and is wider than 

 those in the other two geographical types. 



In both Gulf type and Atlantic type, the pos- 

 terior lobes in the trunk are usually less pro- 

 nounced, and there are no anterior lobes. These 

 anterior and posterior lobes are, however, 

 present and well formed in the Caribbean type. 

 A fully grown ovigerous female of an Atlantic 

 type is much larger than those of the Gulf type 

 and the Caribbean type. The following data 

 were derived by considering all collections from 

 a general geographical region as a whole to 

 show the size ranges (in millimeters) of the 

 ovigerous females of the three different geo- 

 graphical types : 



Smallest., 



Largest. 



Longest egg sac. 



Caribbean type 



Mm. 



1.36 



(in USNM 42251) 



2.14 



(in USNM 42273) 



2.78 



Gulf type 



Atlantic type 



Mm. 



1.51 

 (oil Cape San 

 Bias, Fla.) 



2.51 

 (Carrabelle, Fla.) 



4.09 



Mm. 



1.59 

 (in USNM 38625) 



3.16 



(In USN.M 47748) 



4.61 



Thus, the shape of the trunk indicates that 

 the Gulf type is closer to the Atlantic type than 

 to the Caribbean type, but the size of the trunk 

 indicates that the Gulf type is, on the contrary, 

 closer to the Caribbean type than to the Atlan- 

 tic type. In other words, comparisons of the 

 trunk show that the Gulf type is intermediate 

 between the Atlantic type and the Caribbean 

 type. The variation of the head, in the Atlantic 

 type, instead of the Gulf type, shows the inter- 

 mediate character in the bilobed condition of 

 the lateral wings. 



I have found specimens in USNM collections 

 (Cat. No. 38625 and 74375), from Beaufort, 

 N.C., which, instead of having the Atlantic type 

 trunk, have the po.sterior lobes of the trunk 

 fairly well defined as in the Caribbean type. 

 Moreover, in the collections from Jamaica, some 

 individuals lack the anterior lobes in the trunk, 

 as shown in fig. 27. It appears, therefore, that 

 the variation in the head and the trunk is not 

 absolute, or, in other words, that this variation 

 is merely a general tendency of modification 

 that exists in a certain geographical area but is 

 not strictly expressed by every individual of 



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U.S. FISH AND WILDLIFE SERVICE 



