studies on marine Ostracods 57i) 



the former genus this antennii does not bear any close resemblance to the two latter genera 

 either in its bristles or its musculature. 



The first, second aiul third joints of both the male and female first antennae in the genus 

 Euconchoecia are quite without bristles. The fourth joint of this antenna has ventrally in both 

 sexes a large number (about twenty or more) of sensory filaments of the same type as the two 

 sensory filaments on the next to the distal joint of the first antenna in the genus Halocypris. 

 The end joint has four or five bristles on the male first antenna, and a somewhat smaller number 

 in the female (in most cases one bristle less than in the male?). It seems at present to be quite 

 impossible to carry out a homologization between the bristles on the two distal joints in the 

 genus Euconchoecia on the one hand and those of Halocypris-Conchoecia on the other. 



In the genus Euconchoecia this antenna is characterized by the following muscles : Male (type 

 E. Chierchiae; cf. the accompanying fig. 12 of this species): First joint: Three muscles penetrate 

 from the body into this antenna; two of these run ventrally and one dorsally in the first joint; 

 they are all moderately strong. The dorsal one of these three muscles is attached distally dorso- 

 medially on the proximal boundary of the second joint — the extensor of the second joint. 

 Of the two ventral ones one has its distal attachment proximo-ventrally on the second joint, 

 the other at the corresponding place on the third joint — the flexors of the second and third 

 joints. Besides these three there are two more nmscles in the first joint, an extensor for the 

 second joint and a flexor for the fourth joint. The former of these two muscles is moderately 

 strong and has its proximal attachment proximo-dorsally in the first joint and its distal attach- 

 ment on the proximal boundary of the second joint, dorso-laterally. The latter of these two 

 muscles is very strong and has its proximal attachment on the medial side of the first joint at 

 about half the height of this joint, somewhat proximally of the middle; distally it is attached 

 at the proximo-ventral corner of the fourth joint. — The second joint has two muscles, both 

 of which are powerful. One of these has its proximal attachment proximo-dorsally and laterally 

 in this joint, and its distal attachment on the proximal boundary of the third joint, dorso-laterally. 

 The other is proximally attached on the proximal boundary of the second joint, medially, at 

 about half the height of the joint; its distal attachment is on on the proximal boundary of the 

 third joint, medially somewhat ventrally of half the height of the joint. (The former of these 

 two muscles seems to move the third joint outward and upward, the other moves the same 

 joint downward and inward.) — Third joint: V^entrally in this joint there is a moderately strong 

 muscle, proximally attached proximo-ventrally in this joint, distally at the proximo-ventral 

 corner of the fourth joint = the flexor of the fourth joint. Dorso-proximally in the third joint 

 there is attached the extensor of the fifth joint, a powerful muscle with its distal attachment 

 at the dorso-proximal corner of the fifth joint. In addition there are in the third joint two 

 rather strong muscles, one medial, the other lateral, with their proximal attachments near the 

 proximal attachment of the extensor of the fifth joint and their distal attachments medially 

 and laterally respectively on the proximal boundary of the fourth joint at or somewhat dorsally 

 of half the height of this joint. (These two muscles, which are, for practical reasons, only 

 indicated in the accompanying figure 12 of E. Chierchiae, seem to move the fourth joint inward 

 and outward respectively and somewhat upward.) — The fourth joint h;is only one muscle, the 



