Paeromopidae Californiulidae Paeromopodidae is a family of large cylindrical millipedes of the order Julida native to the western United States of America.

The family contains two genera and ten species and includes the longest millipedes in North America, with individuals reaching up to 16.5 cm (6.5 in) long.

Paeromopodids have distinct parallel grooves called striae on their body rings that give a somewhat roughened texture and distinguishes them from other cylindrical western millipedes.

[1] Paeromopodids are endemic to the United States and occur in two distinct areas: the first is a large Pacific coast range extending from Washington state to the southern Sierra Nevada and Death Valley region of California and east to the Warner Mountains straddling the borders of California, Oregon, and Nevada; and the second is a region spanning extreme northeastern Oregon, across the Idaho Panhandle to western Montana.

[1] C. blechrostriatus inhabits the arid eastern slopes of the Sierra into Death Valley, and has been found at elevations of up to 2,400 m (8,000 ft).