FLEMINGER: INTEGUMENTAL ORGANS IN GENUS EUCALANUS 



Length measurements were carried out with 

 the aid of a stereomicroscope at 24 X and 40 X 

 magnifications depending on the size of the 

 species. The microscope was equipi)ed with a 

 mechanical stage and an eyepiece reticle bear- 

 ing a ruled scale of 100 divisions. Total length 

 (TL) was taken from the right lateral view in 

 two steps: one measurement along an imaginary 

 line extending from the anteriormost tip of the 

 forehead to the dorsalmost juncture between 

 prosome and urosome (Fleminger, 1967) and 

 the second along an imaginary straight line 

 from the dorsalmost juncture of prosome and 

 urosome to the posteriormost point on the right 

 furcal ramus omitting the setae. 



Examination of specimens for perforation 

 number and distribution was carried out with 

 the aid of a compound microscope equipped with 

 a mechanical stage at magnifications of 150 X 

 to 600 X. A camera lucida was used in the 

 preparation of drawings to approximate spatial 

 arrangement of perforations in each form. 



The outline drawing with perforations was 

 reproduced by electrostatic duplicating machine 

 for use on subsequent specimens of the species 

 as a data recording form. Allowance was made 

 for small variations in the distance between 

 regularly occupied perforation sites; all missing 

 and additional perforations were recorded on 

 the form together with length measurements, 

 sample, and specimen number. No attempt was 

 made to estimate variability in the distance 

 between adjacent perforations. 



GENERAL OBSERVATIONS 



Three general types of sensilla were found in 

 Eucahviu.'i (Figures 2, 3). They resemble re- 

 latively simple types found in other arthropods 

 (e.g., see Snodgrass, 1935; Bullock and Hor- 

 ridge, 1965; Schneider, 1969) and are as fol- 

 lows: 



1. Hair (trichodea) sensilla (Figure 2d); 

 slender, elongated, uniformly attenuated, and 

 unarmed; roughly 20 to 150/j in length and 1 

 to 5jU in diameter at the base; observed only on 

 thoracic segments II to V. 



2. Peg (basiconica) sensilla (Figure 2g); with 

 pointed or rounded apex, ranging from 14 to 



27^( in length, 1 to 3|U in diameter; they are 

 widely distributed over the prosome and usually 

 occur adjacent to the pore of an integumental 

 gland. 



3. Pit (coeloconica) sensilla (Figure 2i): 

 shallow circular depressions in the integument, 

 3 to 6ii in diameter, the center raised in a nipple- 

 like protuberance that stains intensively in 

 CBE-lactic acid; they were observed in few 

 species and only on the cephalon and anterior 

 thoracic segments. 



As a rule the sensilla are lost during the 

 course of tissue digestion and staining. Perfora- 

 tions representing the sites of sensilla in pre- 

 pared specimens appear under the light micro- 

 scope as simple round openings. The innermost 

 margin stains noticeably lighter than the 

 surrounding integument. Large perforations 

 (^ ijj) from large hair sensilla may have a 

 craterlike margin on the outer surface (Figure 

 2e). Under the light microscope the walls of the 

 perforation may slope to form a larger elliptical 

 outline on the inner surface of the integument. 

 Perforations derived from pegs are simple and 

 about 1 to 2/j across (Figure 2h). Perforations 

 derived from pit sensilla appear as a pair of 

 very small openings separated by a slender 

 ridge (Figure 2j). One or more of the three 

 types of sensilla were found on all segments of 

 the cephalon and thorax. One aesthetask-like 

 sensillum, usually weakly plumose, is present 

 distoventrally on the furcal rami in all species. 

 No other sensilla were observed on the urosome. 



The other class of cuticular perforations are 

 formed by the ducts of underlying integumental 

 glands (Figure 2b). The glandular pore tends 

 to vary from a semicircular to a slitlike opening 

 of 4 to Ijj across the maximum dimension when 

 viewed from above (Figure 2f-j). The margin 

 stains as intensely as the surrounding cuticle 

 and at least a section of the circumference turns 

 inward toward the underlying hypodermis. 



My use of the term pore in connection with 

 integumental glands does not imply relation- 

 ship to a different integumental feature, pore 

 canals (Richards. 1951) discussed below. 



Microscopic examination (300 X to 600 X 

 magnification) of intact specimens, especially 

 those belonging to the elongatus group (treated 



973 



