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SCIENCE. 



[N. S. Vol. XIV. No. 356. 



9. ' The Larva of Pyrrharctia Isabella as 

 an Anatomical Sabject ' : E. P. Felt, N. 

 Y. State entomologist, Albany, N. Y. 



The availability and desirability of this 

 larva is shown and a few general state- 

 ments made in regard to its internal anat- 

 omy. Attention is also called to an in- 

 ternal parasite and its relations to its host. 

 Two small drawings illustrate the paper. 



10. ' On the Development and Evolution 

 of the Scolytid Gallery ' : A. D. Hopkins. 



This paper embraces some of the results 

 of the author's special study of the galleries 

 of the large number of described and many 

 undescribed North American Scolytidse, to- 

 gether with those figured from all countries, 

 so far as available ; representing in all 

 some 400 species, 37 genera, 13 sub-groups, 

 7 groups and 3 subfamilies. Brief refer- 

 ence is made to the structural character, 

 and characteristics of habit, which distin- 

 guish this family of beetles. In the gal- 

 leries three fundamental forms, or types, 

 are recognized : (1) The longitudinal, (2) 

 the transverse, (3) the broad, irregular 

 chambers which, modified or combined, 

 form the specific types of all galleries, and 

 these seem to fall naturally into eight 

 primary groups and thirty-two divisions. 

 The primary groups are designated as fol- 

 lows: (1) The primitive forms; (2) broad, 

 irregular, branching forms; (3) the am- 

 brosia galleries ; (4) the intermediate or 

 transverse branching forms ; (5) the longi- 

 tudinal, branching forms; (6) the double, 

 transverse; (7) the double longitudinal; 

 (8) the single longitudinal, or higher forms. 

 The paper is illustrated by numerous lan- 

 tern slides from photographs, and by draw- 

 ings of typical forms of galleries ; also by a 

 chart which shows the relations of the 

 various genera, sub-groups, groups and 

 sub-families, to the groups of galleries, in 

 horizontal and vertical spaces. The vari- 

 ous forms of the galleries throughout the 



family, so far as observed, range from the 

 simplest longitudinal burrow (excavated in 

 decaying bark or wood), as the primitive 

 type, to the complex or composite form 

 (with its many radiating branches from a 

 central chamber), as the intermediate, and 

 to the short, straight, longitudinal egg gal- 

 lery (with its symmetrical radiating brood 

 burrows in living bark), as representing 

 the highest type. It is seen from a study 

 of this diagram, that a group of allied 

 forms of galleries does not necessarily rep- 

 resent any single group of species, but that 

 the several groups of galleries represent 

 parallel or periodic stages and relations in 

 the evolutionary development of all the 

 groups. 



Thus if the characters, as expressed by the 

 gallery, are properly interpreted as indicat- 

 ing a stage or period in the evolution, and 

 are studied in connection with structural 

 characters of the insects, it will indicate 

 the natural position of a species, in its re- 

 lation to other species in its group, and to 

 similar stages and periods in other groups. 

 The results of this line of study and thought, 

 incompletely expressed as they are in this 

 paper, may serve at least to suggest the 

 course of evolution of the scolytid gallery 

 within the maximum and minimum limit 

 of an instinctive idea or tendency common 

 to all individuals of the family, but ex- 

 pressed in varying degree as the different, 

 low, intermediate and higher species and 

 individuals are capable of expressing it. 

 This suggests a parallel with the social de- 

 velopment of the human species, in the 

 evolution of the idea common to all, of 

 constructing a habitation in which to rear 

 and protect a family of offspring, as has 

 been expressed in varying degree from the 

 simplest to the highest perfection. It may 

 suggest the importance of considering the 

 law of parallel development of characters 

 and characteristics, in species of remote, as 

 well as near, affinity, and thus enable us to 



