64 Proceedings of the Biological Society of Washington. 



and the anus varies from 17-13 plates. Thus the distance between the 

 navel and the first ventral varies 12 plates and between the navel and the 

 anus varies 5 plates. The range of variation of the ventrals is 11 plates. 

 These figures seem to indicate that whatever variation takes place in the 

 ventral series, takes place anterior to the navel, which itself varies about 

 4 plates. 



Dorsal Scale Rows. — The extremes of variation in this character shown 

 by this series of specimens is 23-25-23-21-19 and 21-23-21-19-17. 



The normal method of row dropping for this species seems to be 25 — VI, 

 23 — V, 21 — VII, 19 — IV. The variation in this character can be shown 

 better in the following tables. One point, however, may be made now. 

 In the mother the 19 rows are reduced by dropping the third row. Most 

 of the young also drop the third row in reducing from 19-17, but this is 

 not the usual method with others of this species, or with other species of 

 this genus, a good many of which have been examined. 



The 23 count is usually reduced just posterior to the gall bladder. 



The Arabic numerals are used to indicate abnormal row-dropping, and 

 show actual row dropped in count from belly at point dropped. 



I. 23-25-23-21-19 ( + VI— VI— V— VII ) 

 Caudals 



64 



Intermediate. 23-25-23-21-19-18-19 ( + VI— VI— V— VII— I V+ IV ) 

 (The mother) 



C 23+VI 25— VI 23— V 21— VII 19— IV 18+IV 19 



—5 —4 —4 —3 +3 



67 37 39 60 70 87 86 101 108 —126 —128 Cont. 



Intermediate. 23-25-23-21-19-1 7-18 ( +VI— VI— V— VII— IV + IV ) 



67 



II. 23-25-23-21-19-17 (+VI— VI— V— VII— IV) 



C 23+VI 25— VI 23— V 



—5 

 68 36 52 41 58 84 85 



