446 TAGE SKOGSRERG 



figs. 3 and 4). List: Inside the ventral margin of the shell this is more or less narrow, either 

 quite without bristles or only with a very few short ones. Inside the posterior margin of the 

 shell it is developed as a comparatively broad, hyaline lamella of uniform breadth and is provided 

 with a somewhat varying number of soft, hyaline, somewhat sword-shaped spines and with 

 a greater or less number of more or less short, fine, stiff, simple, bare bristles. The hyaline 

 spines are often so transparent that they cannot be seen with full certainty, but their number 

 is easy to verify by means of the oval fixing areolae. It is also very difficult to establish their 

 length, for when the shell is looked at from the inside through the microscope, they are in most 

 cases directed towards the eye of the observer; the length that I have drawn in the accompanying 

 figures may often consequently be not quite correct. The latter part of the list is called in this 

 work, as will be seen below, ,,the spine-bearing list" and forms a rather good species character, 

 as the number of hyaline spines and bristles is often rather different in different species, but 

 varies only slightly within each species. On the inside of the shell, on the rostrum, inside the 

 incisur and between the list and the margin of the shell there are a varying number of simj^le, 

 smooth, stiff bristles varying somewhat in length, which, on account of their number, length 

 and especially on account of their situation, provide good characters for the species. Between 

 the spine-bearing list and the posterior margin of the shell there is in a number of species a smaller 

 number of broad pores and close to these a greater or less number of fine ones; the former were, 

 at least in a number of cases, provided with low, hyaline pegs (which are protrusible?), the fine 

 ones do not seem to have either jDegs or bristles. (The latter, the fine pores are called by 

 G. W. Mt'LLER, 1894, p. 219, .,kleine Spitzchen", the inner medial bristles on the rostrum are, 

 on the other hand, called pores by the same author, ibid.) The shell is rather strongly calcified'. 

 The forms are moderately large. 



Male: — This differs from that of the female as a rule by its greater length, though 

 sometimes the female may be somewhat longer (cf. A. curta) and by the fact that the posterior 

 part of the shell is somewhat lower. The wreath of hair round the posterior part of the shell 

 is sometimes rather sparse; it consists of very fine hairs. 



First antenna: — 



Female: — This is very powerful and rather short and has its joints very much 

 flattened from the sides. It has six or seven joints, according to whether the third and fourth 

 joints are free or are united to each other; but even when these two joints are obviously free, 

 they seem to have only a rather slight power of moving mutually; traces of the original boundary 

 between them can always be discerned. The first and second joints are subequal and are each 

 about as long as the total length of all the other joints. The third and fourth joints differ very 

 much in shape from the other joints, as they are more or less triangular; tlie posterior edge of 

 the third joint and the anterior edge of the fourth joint are very much shortened. The shape 

 and the relative length of these two joints afford rather good characters for the species. The 

 two next distal joints are always well developed and rather large; the end joint is small. All 

 the species investigated by me appeared to have almost the same equipment of bristles. The 

 second joint lias on the anterior edge near the distal boundary a single rather powerful bristle, 

 usually pointing forward and bent somewhat upwards, about as long as or rather slightly longer 



